Starfish ID please

[Noodles]

I just noticed a couple weeks ago that I had a "new" starfish, and tonight I found a second one. They're aprox 16-19 mm across. They look a lot like astrea stars but a lot bigger (and they both have 5 arms). They seem to be grazing on the rocks and leaving corals alone so I'm not too worried, just curious what they are:)


Top
http://i1249.photobucket.com/albums/hh517/sheppner/7A783B08-0434-468A-A777-6EEA5A021740.jpg (http://s1249.photobucket.com/user/sheppner/media/7A783B08-0434-468A-A777-6EEA5A021740.jpg.html)

Bottom
http://i1249.photobucket.com/albums/hh517/sheppner/31ACF8E8-4A47-4348-87A6-6A70F5E9545A.jpg (http://s1249.photobucket.com/user/sheppner/media/31ACF8E8-4A47-4348-87A6-6A70F5E9545A.jpg.html)

[strider]

What color are the from top?
Grey/white?

I just looked into my tank. They are asterina. I have tons the are on rocks, glass and everywhere else.

They will eat algae and dead matter.
I thought they were eating my Zoa but on close inspection I realized they were cleaning the dead ones and not bothering the healthy polyps.

[Myka]

Asterina sp starfish. I used to think they are harmless (some species of them are), but some are definite coral predators. I consider them all pests and remove any I see.

[Noodles]

Yes, white with grey marbling.