Hairy leg crabs, friend or foe to Acros?

[todd williams]

I have recently increased my acro community and have acquired three different species of acro crabs. Someone has told me that one, a greenish/ black crab that has hairy legs is a pest and should be removed. It is small a little bigger than my pinky nail. I was told they will eat polyps. It has recently moved to a new acro which has me thinking. Can anyone let me know if this is a pest or is it ok?

My other two crabs are pink ( like cooked lobster) coloured and reddish coloured.

Thanks to any that reply.