Sessility (motility)

Sessility is the biological property of an animal describing its lack of a means of self-locomotion. Sessile animals for which natural motility is absent are normally immobile. This is distinct from the botanical concept of sessility, which refers to an organism or biological structure attached directly by its base without a stalk.

Sessile animals can move via external forces (such as water currents), but are usually permanently attached to something. Organisms such as corals lay down their own substrate from which they grow. Other animals organisms grow from a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull.^[1]