Jelly

pull one side. the other side answers late.

pull a jelly on the table, let go, and watch the wobble travel through before it settles

Push a soft body and the push does not move it at once; it travels through, so the far side stays put for a moment, then overshoots. That delay is what separates a jelly from a solid.

Concepts: elasticity, waves, soft-body.

An interactive you play with one thumb, on Wundr.