What might this be?

[pleco]

Saw this on my coral...any ideas?

 

[frisbee]

Asterina star. Some people consider them to be reef safe, but I don't trust them. As soon as I see one it gets tossed ASAP.

http://reefkeeping.com/joomla/index.php/current-issue/article/45-reefkeeping-101-

http://www.coralpedia.com/index.php?module=Gallery2&g2_itemId=1426

http://chucksaddiction.com/coraldisease.html

 

[SantaMonicaHelp]

It looks like a scary spider to me, but yes, it's an asterina =)