[1] When underwater, it extends 48 short tentacles arranged in 3 whorls.

Some may have green or brown coloured tentacles due to the presence of a symbiotic algae known as zooxanthellae which may provide nutrition.

[1][3] Its column varies in colour from white, grey and green to bright orange.

It is covered with white warts (verrucae) to which pieces of sand and shell become stuck.

Its mouth is brown that fades to white or yellow towards the margin.