Asterina gibbosa, commonly known as the starlet cushion star, is a species of starfish in the family Asterinidae.

[3] Asterina gibbosa is mainly nocturnal, spending the day underneath boulders, overhangs or in caves, or hidden away under algae in rock pools.

It is an opportunistic scavenger but the bulk of its diet comes from the film of bacteria and diatoms that exist on the surface of rocks.

It feeds by everting its stomach (turning it inside out) against the surface of the rock and secreting enzymes which digest the film.

Other foods found in its stomach included decaying toothed wrack (Fucus serratus), periwinkle faeces and bits of dead molluscs such as mussels (Mytilus edulis), oysters (Ostrea edulis) and periwinkles (Littorina littorea), but 95% of the stomachs contained no large particles indicating the importance in its diet of microscopic organisms.

It is found from the lower shore down to a depth of about 125 metres (410 ft) in pools, on rocks, under boulders and overhangs.