I do have those snails and I was wondering if that was what they were I have seen the snails crawling on them but have not seen them depositing them.
not to go off the key of the thread but I might say you have a really bad aptasia problem.. just judging by the pics...........
You have no idea just how bad, it started out with a half dozen or so and my wife was throwing a fit about me killing them and they weren't spreading for about 6 months and then after I moved my aquarium they went crazy and now I have over 300
and I am having difficulting finding something to kill them off have been trying to get joes juice from lfs for 2 months, and they also have not had any livestock that will eat them, so I have been trying to get some kalkwasser and try that but have not been able to track that down locally either so in the meantime the aptasia is ruling my tank.