What's eating my torch coral?

[Phyto]

There is a cottony-like, fibrous tube going up the side of my coral skeleton. It appears to be coated lightly in sand on the outter surface of the tube. The tube begins from my live rock to the head of a torch coral. It seems to be eating at the head of the torch, as it looks irritated. I destroyed the tube and moved the coral. I found no organism in the tube., Any idea what this is?

 

[graveyardworm]

Sounds as though it may have been a sponge growth.