what are these white root looking things?

[mseepman]

Those sponges just keep coming and they become a nuisance quickly. Get rid of them if you can.

[windcoast reefs]

I just leave the sponges, some of my fish eat them so it don't find them a problem. The little brittle stars are also Fi e in my opinion. I've never had a problem with them.

[Myka]

Mini brittle starfish I've never had a problem with and find them beneficial scavengers, but I have had some Asterina starfish that were, at the very least, suspect. I'm pretty sure that I had some Stylophora eating Asterinas in my tank. I put a Harlequin Shrimp in the tank and cured the problem.