Each glyph starts as a single-stroke skeleton dropped into a bath of simulated nutrient. The nutrient diffuses in from the edges; ink consumes it; empty cells touching ink accrete with a probability set by how much nutrient reaches them. Tips that reach into fresh nutrient grow fast and screen the hollows behind them — which is why the growth throws thorns, the same reason frost ferns and corals do. Growth only ever adds, so the four weights nest: Overgrown contains Thicket contains Sprout contains Seed, cell for cell.
Nobody drew the outlines. The letters were grown on a GPU, photographed at four moments, and traced into a real font. The thorns are not a texture applied to an alphabet — they are where the growth actually went.
94 GLYPHS × 4 WEIGHTS
The 47-second film shows the whole alphabet growing in real time, scored by the growth itself — every crackle is cells accreting. Watch GROWN on YouTube.
Free for any use including commercial, under the SIL Open Font License 1.1. Modify it, embed it, sell things set in it — just don't sell the fonts by themselves, and call any fork something other than Accretion. Skeletons descend from the public-domain Hershey fonts (Dr. A. V. Hershey, U.S. Naval Weapons Laboratory, 1967).