What is my coral growing on??

[avocadoman]

My favites seems to be growing.... around some tubular structure that also seems to be growing with it. Is this some kind of worm or something?





Also, I had this sort of clam looking thing appear on my rock recently. Maybe 8-10mm wide. What is it?

 

[Nate Chalk]

My favites seems to be growing.... around some tubular structure that also seems to be growing with it. Is this some kind of worm or something?





Also, I had this sort of clam looking thing appear on my rock recently. What is it?

Is it a flat worm?

Vermited snail?