Sorry for poor photo. I noticed what looked like a 4/5 inch worm going from a zoa up to a piece of rock. It is very dark green/black in colour - it looks to have some sort of ‘claw’ (see end of curved piece) which was attached to the zoa. I when I pulled out it didn’t move and seemed to be some sort of plant material - and if pressed gave off a ‘cloud’ of something. Anyone have an idea what it is please. It was attached to the underside of the rock. Can’t see anymore in the tank but you never know.