I saw a pure white star the other day in my tank. He was small, not even 1/2 inch accross. What do you think it is, and is it reef safe? Also, this is the first time I have seen him, and I haven't added any LR in 4 months.
The question is, is it a starfish or a brittlestar. To tell the difference, starfish have stubby legs and a central disk area that is not distinct. Brittlestars have a central disk that is distinct, and 5 thin arms extending out.
There are small white versions of each of these that are hitch-hikers in our tanks
The small white brittlestar is Amphipholis squamata. It is a self fertilizing hermaphrodite, which will reproduce quickly given good conditions. It is considered very beneficial for tanks...but you may never really see them.
The small whitish seastar has 5-7 arms, some of which may be unequal. It reproduces by splitting in half. There are probably 3 species, and it is virtually impossible to ID them, except based on what they eat. If you see it randomly on the glass and rocks, it is an algal and bacterial film eater. However, there is an SPS eater as well, so watch out if you see them on corals. Remove them if they are on corals. I have them in my 15g nano and they are reproducing, but I do not have SPS corals...clearly they are not all bad, so don't let overreaction scare you. You may see people saying they are all trouble, but certainly if they are on the glass, they are not likely to be trouble. The genus is Asterina and you can search for this and find lots of posts. There is one probably every week
Based on your descriptions, I would say it is the starfish. I saw it on the rocks. I went to get my book to try and I.D. it and it was gone. I haven't ever seen it before, and it wasn't by my corals, so I'll just hope it's a nice one. Thanks.
I found both kinds in the same tank on the same day. I'm just going to keep an eye on them as I only saw the brittle for a few seconds, and the starfish for a few hours on the glass. If I see one on the corals, out it will go.