This starfish has five tapering, blunt-tipped, arms covered with small, scattered white spines. Small specimens are quite stiff but larger ones are rather soft and floppy. The white spines form a definite line down the centre of each arm. Between the spines are groups of soft transparent processes called papulae. Body colour is usually brown to pale orange, in some locations this may be masked by blue or purple. In exposed habitats up to 12cm, in more sheltered sites up to 30cm across. Leptasterias muelleri
is a smaller species and can be distinguished by its firmer spinier texture and characteristic spines.