A cell's membrane, pushed out by its pressure and pulled in by its cortex, in 3D and then in 4D. The colour is the cortex's tension: warm where it's tight, cool where it has let go, gold where a contractile ring or belt pulls. The purple ball is the nucleus, seen through. Drag to turn it. In 4D the pad twists your slice into w (J L, I K), the lever moves it ana and kata (R F), ⊞ or Z squares it up. how it works · TENTACLE · kata