Description: A tiny oval, flattened sea urchin which lives in coarse gravel. When alive its colour is grey-green but on being hurt or damaged it turns bright green. The spines are short and give the animal a velvet texture. The anus is on the underside of the test posterior to the central mouth. Typically only 1cm. in length.

Habitat: Lives buried in coarse gravel where it feeds on detritus and Foraminifera. Difficult to collect owing to its small size.

Distribution: Recorded from all round the British Isles.

Similar Species: Unique, the only member of the order Clypeasteroida in the British Isles.

Key Identification Features:

• Tiny oval sea urchin.
• Turns green if damaged or preserved.
• Anus on underside of test.

Distribution Map from NBN: Echinocyamus pusillus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Echinocyamus pusillus at iNaturalist World Species Observations database.

WoRMS: Echinocyamus pusillus at World Register of Marine Species. Accepted name: Echinocyamus pusillus (O.F. Müller, 1776). AphiaID: 124273.

Classification: Biota; Animalia; Echinodermata; Echinozoa; Echinoidea; Euechinoidea; Irregularia; Neognathostomata; Luminacea; Echinolampadacea; Scutelloida; Laganiformes; Fibulariidae; Echinocyamus