What is this bouncing starfish?

[z28cam]

So I was looking at my tank...like I do 50 times day lol and what I thought was a piece of algea or something, starting moving and bouncing. It walks like a drunk spider.

Here's a video I got before it dissappeared Into the rockwork.
http://instagram.com/p/kAILgtHDZ5/

 

[Sugar Magnolia]

It's a sea spider, Pycnogonida. Next time you see it you'll want to remove it. http://reefkeeping.com/issues/2003-01/rs/