Black widow mutant split

[DanConnor]

OK, so I had a black widow split a couple time, and they keep leaving behind these small weird mutant things. I have 3 mutants now, and one is quite big. They are small at first, but they grow and never look like a regular anemone. Exactly the same color, but all frilly. Not particularly responsive to touch. Is it possible it isn't an anemone at all but just appeared at the same time. Gelatinous. The picture is a regular and mutant together.

 

[LiveFreeAndReef]

Funky!!

 

[DanConnor]

On further investigation, I'm pretty sure its an algae, although I never would have guessed it. Probably Predaea weldii.
The photo here looks exactly like it
http://www.seaslugforum.net/showall/miscalgae