Two Red Legged Hermit Crabs One Shell

[Caitlinmcdonald]

I have a red legged hermit crab in a saltwater tank all by itself because it is aggressive and kills my snails. I checked on him today to see if he was okay and I saw a dead one on the ground. When I went to move the shell there was another red legged hermit crab in there!!!
Someone please explain what the heck happened.

 

[Reefing102]

Looks like he molted - normal growth process

 

[wvned]

Molts can look exactly like the crab/shrimp.