Not sure what this is - appeared on the side of my TBS live rock. Kind of clear-ish, not sticky to the touch, more firm to the touch - just weird. I had a feather duster close by that had attached its casing to a half clam shell and this blob looked like it grew under that clam shell and then started to move out into the sand. I pulled as much as I could from the clam shell and moved the feather duster.