Sheet 04a · Murmurs · drawn by W.

Murmurs, in detail

A tide pool of creatures that breed. What it is, everything it can do, and how one curve and eighteen constants end up behaving like genes.

notes on a tide pool

Open the tide pool →

What it is

A pool of small creatures, each one drawn entirely by arithmetic. They swim, they can be bred with one another, and their offspring inherit and mutate. Five founders come with the pool and the tide never takes them — though you can let them go yourself if you would rather start from nothing. Everything after them is yours to name, keep or release.

It runs in a browser with nothing to install. Your pool lives only in your own browser — it is not uploaded, not shared, and not visible to anyone else, including us. Export it to a file if you want to keep it or move it.

The creatures are not ours. The curves that make them were written by @yuruyurau, who posts in the Japanese #つぶやきProcessing tradition — sketches golfed small enough to fit inside a single tweet, code and all. Tsubuyaki means murmur. That is where the name comes from and it is the whole of the credit they carry: the animals are theirs, the pool is ours.

Everything it can do

Three views, reached from the tabs at the top of the panel: the Pool, the Jar, and the Study table. Press H at any time to hide the whole panel and just watch the water.

The pool

Click any creature — in the water or on its card — to select it. Select two to pair them.
Breed two residents by hand, or leave the tide to pair them on its own.
Every creature can be renamed, founders included, with the pencil beside its name. Newborns arrive with a suggested name you can overwrite.
Bloodlines draws the family tree: founders on the top row, each generation below, descent lines coloured by the parent they come from.
Choose how names are suggested — invented, blended from both parents, or a mix of the two.
The tide never takes a founder, but let go removes one deliberately, and Restore founders brings all five back whenever you want them.

The jar

A second body of water. Move a creature there and it is out of the running entirely: never culled and never chosen by the tide.
It is where the ones you want to keep go. Move them back whenever you like.

Recently gone

When the pool is full the tide takes the oldest non-founder — but nothing is destroyed straight away.
Anything taken waits here and can be brought back, arriving safely in the jar. The last twenty-four are held.

The study table

Every constant of the selected creature as a named slider — between eighteen and twenty-two of them, grouped into body, motion, shape and multiplicity, and different for each body plan.
Switch body plan outright, and the sliders rebuild for that form.
Forty-five wild specimens, nine per body plan — interesting corners of each form's parameter space.
Mutate for a nudge, Wild for a shove, Revert to undo it all.
Apply writes your edits back to that creature; Release as new adds the result as a separate one and leaves the parent alone.
Founders can be edited freely but never overwritten — their original form is always kept.
The live p5.js source for whatever is on the table, with your numbers in it, ready to copy and run elsewhere.
Copy link puts a single creature in a URL. Send it to someone and it opens on their drafting table.
Double-click any slider to reset just that one.

Heredity

Mutation rate — how often a gene shifts when passed on. At zero, children are pure recombinations of their parents.
Mutation size — how far it shifts when it does.
What it inherited: for any creature with parents, a gene-by-gene readout of which parent each gene came from, which were blended, and which mutated on the way.

Colour

Twenty-four palettes, fourteen of them travelling through several hues — nacre, an anglerfish's cold body and single warm lure, copper corroding to verdigris, a bruise healing from purple through olive to yellow, and a full pastel rainbow.
A gradient control that switches which axis colour follows: density by default, or position along the creature's body, head to tail.
Colour drift — how much a child's colour can leave its parents', including the occasional sport: a colour from nowhere that then breeds true. Gradients also arise on their own, and are lost again just as readily, so the pool stays a mixture rather than turning wholly one way.

Life

Biolight — a singing creature lights up in time with its own voice. Each note sends a band of light travelling along its body, swelling it as it passes.
Birth bloom — a newborn's points arrive scattered through the water and gather into shape as it grows.
Shed light — creatures leave motes of their own colour drifting behind them, so the water keeps a record of who passed through.
Courtship — a pair selected for breeding drift toward one another and their colours bleed together until the birth.
Distance — the ones further back are smaller, dimmer and colder, so the pool reads as a volume of water rather than a flat pane.

The tide

Flow — how fast the creatures move. At 1, each species runs at exactly the tempo it was originally written to run at.
Wander — how far and fast they roam the pool.
Birth interval — minutes between one tide and the next.
Population — how many the water holds before the oldest is taken.
Reset all settings restores every slider and touches no creature, name or bloodline.

The water

Density (detail), exposure, glow, trails, dot size and overall size.
Marine snow drifting down beneath the creatures, and water — the dark closing in at the edges, cold at the top, heavy at the bottom.

Song

A selected creature sings; the pool is silent otherwise. Select two for a duet.
Whale song, synthesised on the spot — no files, nothing downloaded.
Its voice comes from its genome, so it always sounds like itself, and its children inherit something of it. The phrasing is built fresh every time, so nothing repeats.

Keeping and capture

Save PNG at one, two or four times screen size.
Record the pool to a video file straight off the canvas.
Export the whole pool — every genome, name, colour and bloodline — to a single file, and import it back on any machine.

Keyboard and mouse

H hide the panel · Space hold the water still · B bloodlines · S save a picture · M mutate (on the study table) · Esc close.
On the study table, drag to reframe and scroll to zoom.

III

How one creature works

There is no model. No mesh, no skeleton, no physics. A Murmur is twenty thousand points strung along a single parametric curve, folded through a chain of nested sines and redrawn from scratch every frame.

The loop walks one number — call it y — from one end of the body to the other. At each step, roughly a dozen lines of arithmetic turn y and the clock into a position on screen. Plot all twenty thousand and an animal appears. Advance the clock a fraction and it swims.

The creature is not drawn. It falls out of the arithmetic, and it moves because the numbers move.

This is why they look the way they do. The fine dotted texture along a fin is not a texture — it is the sampling rate of the curve, made visible where the curve doubles back on itself. The soft glow in the dense regions is thousands of points landing in the same few pixels.

The constants are a genome

The original sketches are full of bare numbers. cos(y*5). y/8-13. i%3*8. Each is a decision the author made about what this animal is.

We gave every one of them a name, a range and a slider. That single change is what makes the rest possible, because a named, bounded number can be inherited. A creature stops being a picture and becomes a genome that happens to render as one.

Nothing about that is a metaphor. When two Murmurs breed, the child's comb really is one parent's value or the other's, or a point between them, occasionally nudged.

Five body plans, five clocks

A form is a different curve entirely — a different post, a different animal, its own gene set and its own clock. That last part matters more than it sounds. Each of yuruyurau's sketches advances time at its own rate, and that rate is the animal's tempo. Rather than force them all to one speed, every form keeps its own.

Form	Clock	Reads as
Koi	PI/45	the original — feathered fins, quick
Strand	PI/360	a slow twisting cord, eight times slower
Frond	PI/30	a feathered leaf, the fastest
Spine	PI/80	a ribbed lattice; built, rather than swept
Quill	PI/30	a twisting body with a plumed head

Breeding, and crossing body plans

Two Murmurs make a third. For each gene the child takes one parent's value, or the other's, or a blend somewhere between, and then may mutate.

Crossing two different body plans needed a rule, because there is no halfway between one curve and another. The child takes one parent's form on a coin flip and can only inherit genes from parents that share it. A single donor has nothing to recombine against, so those crosses mutate harder to compensate. Colour still comes from both — so a child can have its father's body and its mother's colour exactly.

VII

Why colour has to mutate

Colour is inherited like everything else: a child takes one parent's palette or a blend of both. Left there, it fails. Blending can only ever produce colours between the parents, so a bloodline converges. Measured over eight generations with mutation switched off, the spread of hues in a line collapsed from forty degrees to under two — every descendant the same teal.

So colour mutates too. Usually a small drift; occasionally a sport, the breeders' word for a colour that arrives out of nowhere and then breeds true. With it on, hues appear that none of the founders had.

VIII

The song

A creature's voice is fixed, hashed out of its own genome, so it always sounds like itself. What varies is the phrasing: how many notes, which pitches, how far each one bends, how long the silences run. Over a minute of listening, no phrase repeated.

The nicest part was free. Vibrato is taken from the form's clock — the same number that sets how fast it swims. A Strand hums at 0.8 Hz, a Frond at 4.6. They sing at the speed they move.

There is a second voice woven through it, made of glass. It arrives in cascades — runs of struck notes climbing or falling across two or three octaves, each one ringing on for seconds after it is struck. The pitches are drawn from a chord built on the same root the creature sings from, so the two lines are always consonant, but the glass keeps its own timing, deliberately not the song's. They drift into alignment and out of it again, which is what makes it sound like two songs rather than one doubled.

A wineglass rim's modes are inharmonic — they sit near 1 : 2.32 : 4.25 rather than at whole multiples. That ratio is the whole reason glass sounds like glass and not like an organ pipe, and it is the only thing about this layer that had to be got exactly right.

And the song is visible. Every note sends a band of light along the creature's body:

the pitch decides where it starts, the note's length how fast it travels, and a rising pitch sends it one way while a falling one sends it back. Where the light passes, the body swells. When two notes overlap, so do the two pulses.

The light is not an effect laid over the animal. It is the note itself, drawn.

What this isn't

It borrows biology's grammar, not its substance. There is no fitness and no selection pressure: the tide pairs at random and culls by age, not by merit. Nothing is competing for anything. What you are watching is drift with a mutation rate — a real process, but only one of the things evolution is made of.

Heredity is recorded from the day the recording was added, so the oldest residents can tell you who their parents were but not what they got from them. They say so rather than guess.

And it is a toy, not an instrument. Nothing here is measuring anything about the world.

credit

The base curves are @yuruyurau's, posted under #つぶやきProcessing. Five of their sketches became the five body plans. If you take anything from this page, take their handle.

The pool, the genome, the jar, the bloodlines and the song were built here, in a workshop across a courtyard, over the course of one long Saturday.

Drawn by W. · House de Lochan · 26 July 2026

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