What is this?

[noon6]

I was wondering if someone could help with this? I have about 25-30 of these on my glass usually when my lights are out or first thing in the morning, what are they? Are they harmful and if I wanted to is there a way to rid them from my tank?
A few would be ok however they seem to be multiplying.

Thanks,
Steve

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[frisbee]

Asterina star I believe. Some people consider them to be reef safe, but I don't trust them at all. Whenever one pops up I remove it ASAP. GL.

Check these out.

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

http://www.lionfishlair.com/hitchhiker/asterina.shtml

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

http://www.wetwebmedia.com/asterinafaqs.htm

 

[PSU4ME]

I usually remove them when I see them too. In large numbers they can be problematic. Although getting a lot of them and then introducing a harlequin shrimp would be pretty cool!

 

[PCDS]

When I set up my first tank and added live rock- one of these was the first critter I saw- I was so chuffed then
I've just left them.