What is this? Crab of some sort?

I've been seeing this thing in my rock from time to time, its always under rock hiding. This is the best image of ever gotten of it. I assume its some type of crab or maybe something else. Any ideas?
http://www.youtube.com/watch?v=ZgIiLNZ__Ew&feature=g-upl&context=G2c3054bAUAAAAAAAAAA

 

bump

 

"An error occurred. Please try again later." is all I get.

 

I honestly have no clue. You sure it isn't algae or something? I've never seen anything like that!

 

Wow thats bizarre and really cool! I have no idea what it is!

 

with the "fans" waving , almost looks like a porcelain crab. if it is , nothing to worry about

 

It's a Porcelain Crab. What you are seeing is it waving it's fans to catch floating food. A very harmless, very cool HH.

 

If its a porcelain crab, cool, just wish I could see it, the only I view I get is with a flashlight under rock. I have noticed that it has grown and am only concerned about my coral or claim being eaten. I wish I could catch it to at least know what it is with its wavers....but it hasnt seemed to do any damage to anything so far, my gsp dont grow but dunno if that due to it or just bad luck wit gsp

 

My first thought was a porcelain crab as well. they are filter feeders and will not harm corals or clams.

 

Porcelain crab for sure! Totally harmless, max size no bigger then a quarter. A good way to see em at night is with the use of an infrared light