I didn't know it at the time but I recently had an infestation of these little guys. I moved a couple months ago and had to put everything in buckets for the move. We put all of the base rock, no corals, in a bucket and did not worry too much about them. there was not a lot of water in the bucket and the water got pretty cold quickly, When we went to take the rocks out and put them back in the tank there were 8 of these worms in the bottom of the bucket. We then proceded to dip all of the rocks and found 2 more.