Prolapsed seahare?

[perverseosmosis]

I came out this morning to find a funny organ-looking thing sticking out of the head of my sea hare. The sea hare still seems to be roaming about, eating as ever. Sometimes the tube seams to shrink down, and then expand back up.

Picture on dropbox

I don't know what would have physically injured it. All my powerheads are covered with foam. Water parameters are good. There's been plenty for him to eat.

I'm hoping this is something like a sea hare boner, and it will pass