IDs PLEASE

So this is my brother's nano tank and while he was doing some maintanence, he saw this nudith looking thing, was wondering if this was a beneficial thing in the tank or if it's a pest, need an ID on this thing. And there are also small tiny clumped spots that were also circled in one of the pictures with his hand in it, was also wondering what that was? And the coral that is circled in the picture that shows the whole tank, can i get an ID on that coral as well please?

 

I have no idea what that nudibranch is. I think we are gonna have to wait for the one of the bigg'uns to chime in on this one. I hope it is safe though because it is cool lookin'! Looks like maybe it (or something) laid an egg mass next to it. As for the coral, it is hard to guess from the picture but I'll throw out Sinularia,some type of finger leather?

 

Awesome flowerpot BTW! Can you get some clearer pics of the nudi and the mystery coral?

 

there are thousands of nudi's only a hand full are safe. some only eat one thing. i bought some star polyp's and the nudi on it only ate star polyp's. like the berghia varrucicornis only eats aiptaisa's