Re-upping. What IS this stuff??

[SallyWho]

I've got this weird fleshy mat of tan/brown stuff growing on my rocks. I took some to work for microscopic review. What do you think it could be? And is it just part of the newish tank uglies and I need to wait it out, or will it become a nightmare? Thanks!

 

[rkpetersen]

Somewhat of a guess, but it could be some unusual dinoflagellate.
I say this because of the matting growth form, and the consistent asymmetric shape of each organism.
Did they appear to move about at all under the microscope? If so then I would suspect a dino even more.
However I could be wrong. I don't recognize it as one of the 'usual' dino suspects.
Personally I'd probably siphon as much as possible out with a water change.