What Type of Shells for Scarlet Hermit Crabs?

[teddscau]

Hey guys. I have a Halloween hermit crab, several scarlet hermit crabs, and some terrestrial hermit crabs. I have plenty of comfy shells for my terrestrial and Halloween (turbos and those somewhat conch-shaped shells with the narrow slot, respectively), but I have no clue what type to get for my scarlets. Their shells are so old that they look like live rock, so I can't figure out what to buy for them.

Does anyone know what specific species of shells they wear? Hermit crabs are extremely fussy when it comes to shells, so I have to pick the perfect ones for my scarlets. Thanks

 

[pagojoe]

Something with an oval aperture, that looks to be about the right size. There are lots of murex, tulip, and triton shells that should work.