The cushion sea star has eight short, distinct, triangular "arms", though 7- or 9-armed individuals can be found.

The cushion sea star is found in the intertidal zone of Australian coasts from Western Australia's south coast to Queensland's coast off Currumbin, while including Tasmania, South Australia, Victoria and New South Wales.

This sea star species favours rocky coasts abiding both in tide pools and to a maximum depth of 3 meters below sea level.

Like other sea stars, the cushion sea star is a slow-moving animal using its tube feet to move about, collecting or subduing the food items that constitute this omnivorous species diet, namely, algae, detritus, mussels and other invertebrates.

This species is viviparous like a few others classified in the genus Patiriella, brooding its young within the body.