Question about crab

We have a little crab in our saltwater aquarium its been just the one for like a year,well today we noticed that we have an extra crab shell that does not appear broken or open in any way complete down to the antlers,and our crab appears a little bigger, we didn't have and couldnt possibly have had a secret other crab in the tank so can anyone explain why we have an extra shell?

I found it! nevermind, well a website with the info,apparently t molted,no wonder she looked more blue!

I am so sorry I totally missed your post. Yes they do molt leave the shell in as it good food for the crab or other inverts you may have.

I agree! I remember picking up molted shells when I was younger at the beach! Id put them in an empty goldfish bowl and use it for a table decoration!

Yep, it probably has molted before now too if you have had it for a year. Just did it in a spot where you couldn't see it. My red legged hermit just molted last week and my coral banded shrimp molts almost monthly. Unless I am cleaning the tank I don't bother pulling out the molts. Even as large as the shrimp is the spaghetti worms & hermits clean his molt up in about a day.