Sea slug shell used by Hermit crab

Sea slug shell used by Hermit crab

Observation - Sea slug shell used by Hermit crab - UK and Ireland. Description: I found many hermit crabs (Pagurus bernhardus) in these unusual shells low on sandy Rhossili Bay, Wasles, in the Sand mason worm zone. I'm now sure the shells are of a primitive shelled sea slug, a predator of sand mason worms which is well known at Rh

I found many hermit crabs (Pagurus bernhardus) in these unusual shells low on sandy Rhossili Bay, Wasles, in the Sand mason worm zone. I'm now sure the shells are of a primitive shelled sea slug, a predator of sand mason worms which is well known at Rhossili.