This was just plain weird looking, happened in about 4 or 5 seconds. I got lucky with the photos. This mushroom just swole up to the size of a golfball and then this crab just kinda popped out. Sorry, I by accident I posted this also in the reef section
the crab was probably out for a stroll and had to poop... then the mushroom smelled the poop and said LUNCH TIME, YESS!! and closed up to eat... then the crab thought...hmmm.. time to leave.