Bad star?

[Kioti]

Hey all, I am still pretty new to marine aquarium keeping. I have a few brittle stars that have come on a coral and I know they are reef safe. However, today I noticed some type of starfish on the glass and I know that several can be harmful in a reef tank. How do I know what kind it is? I can't get a good pic as it is only about 1/4". Any thoughts? Thanks!

 

[Anonymous]

The tiny white stars aren't a problem. It's some species of brittle (not serpent) stars that are a problem, very specifically Ophiarachna incrassata. There are likely other species that hunt as well, but I don't know their generic or common names.

 

[JPagliai]

Based on the size, it sounds like it may be a type of asterina starfish. Some are good, some not so much. There are a couple of varieties. If you see them eating corals, you have the bad ones. If they only appear on the glass and live rock, they are probably algae grazers.