Found two emerald crabs in my acro? Concern?

[spankey]

I woke up today to gather some frags to meet some people to sell and swap, and when I turned on the lights, two of my emerald crabs were in my one acro colony? Why do you think this was? It only concerns me that I hope they weren't nipping and damaging the coral itself?

Anyone ever see emeralds do this?

Thanks
Spankey!