The rear parts of the hermit crab are soft and there is no hard shell to protect this region. He solves this problem by finding an empty shell of a snail and backing into it to make his home. This is how it gets its name. The head has robust ocular peduncles that aren't very long and are dilated at the tip. The left claw is larger than the right and both are a black or yellowish colour at the tip. The claws and feet are both toothed and covered in fine hairs. Colours vary between bright red through to orange. The eyes are bluish and the ocular peduncles have red and white stripes. Specimens have been recorded up to 8 cm in length.
Hermit crabs reproduce between July and August. The larva are symmetrical but as they grow and the soft asymmetrical abdomen develops. The crab uses empty snail shells (which are periodically replaced) for protection. Hermit crabs and the stinging anemone 'Calliactis Parasitica' have a symbiotic relationship and are often found to be sharing the same shell.