I have a 5-6" green/yellow humulis colony that I've had in my tank for about 6 months, it currently has at least 2 acro crabs (or what I think are acro crabs) living inside. It is doing very well and growing but I've noticed what I though was tip damage to a few of the coralites that were healing over, the tips were black on 3 or 4 of the coralite ends. Imagine my suprise tonight that one of the black tips opened up like a mouth and it appeared that there was something living inside the opening at the end of one of the tips! Any ideas? The crabs do not appear to be hairy.
