What the heck is this?

[ClownfishSushi]

For several weeks I've noticed some sort of macro algae stalk growing on an astrea snail in my girlfriend's tank. Today, it blossomed into what could only be described as a central disk. It also appears to have some nearly invisible polyps that it might be feeding with. Is it a worm? An algae? I'm stumped!

 

[ClownfishSushi]

http://en.wikipedia.org/wiki/Acetabularia

 

[Alavaster]

That's Super cool. Absolutely huge for a single celled organism!

 

[SushiGirl]

Oooh, thanks for the ID, I had a tiny bloom of that (4 or 5 stalks in all LOL) in my 20L a while back.

Boy, that snail sure has a collection of bubble algae!

 

[accordsirh22]

lol @ the snail with all those hitchhikers