Who Gives A Fish Forums

So I stopped by Spokane today and picked up this really cool zoa "brick" that my girlfriend loves. I turned off my tank lights, so they're a bit closed up, but they're this awesome green and red color. It even came with a bright green mushroom attached - pretty sweet.

I do have a question, though. There's something hanging off it that looks like a centipede, but it's not a worm. I tried to get a good picture, but all I have is my cell phone camera, so it's not the best. You can see it on the right side of the pic. It's about an inch long in some spots, shorter in others.

I was also told to supplement my corals with plankton once a week - is that right? And when should I start dosing Ca and Mg?

Looks like I've got some unwanted guests, possible bristleworm hitchhikers, though I'm not entirely convinced yet.

Those hitchhikers resemble serpent stars or bristle stars to me - both are harmless, so no need to worry.