Description
Snail fur hydroid colonies form crusts on hard substrata. Specially on shells, occupied by hermit crabs. There are several types of polyps in a colony, with different tasks. The largest ones are for feeding, most of the polyps are for defence, there are cleaner polyps and there are male an female reproductive polyps.

Size
The smallest polyps are 3 mm long, the largest 15 mm.

Colour
The base colour is brown to black. Female reproductive polyps are pink, the male polyps are white.

Habitat
Snail fur hydroid is often found on shells, occupied by hermit crabs, but can also be found on rocks, poles or other hard substrata. Till depths where the sunlight gets through (eufotic layer).

Distribution
North Atlantic ocean.