Are they eating sand?

Question
My two purple pinchers seem to be eating the sand in the crabitat.  That or I'm going crazy because the sand is dissappearing! The sand is calcium carbonate so if they do eat it, I doubt it will hurt them, except for the fact that it's glow-in-the-dark!  I think they probably just need calcium but they ignore their cuttlebone.  Will it hurt them?  I don't think they'll start glowing...That would be so cool though!!! LOL

Answer
They are most certainly eating it. Crabs will eat anything and some really take to calcisand.

Crushed egg shells and fresh shrimp tails are other good sources of calcium. I have tried cuttlebone soaked in fruit juice that is a big hit with mine.

Good luck!