he is 100% gone.... tore my rock apart, checked overflow, floor around tank (even tho i have a lid) a 3-4" tang just doesn't just pull a Houdini and disappear like that. i have no holes in my rock big enough for him to fit into. possible mantis? i am very familiar with the sounds they make and how to spot there burrows but im not ruling that possibility out just yet. i have a long ten anemone but it is not full and plump like it just ate something large. someone mentioned to me that they had a tang MIA after adding powerheads to the tank. ( i just added two koralia 1400s and a skimmer the other day) if you have any suggestions on what you think might have happened it would be greatly appreciated.