This is new to me.

So I found this thing in some of my hair algae last night after lights out, It was twitching like a teen having an epileptic seizure at a rave. When I went to grab it with my tweezers, it starting shaking all this white stuff out, tons of it, like a dandruff problem I'd never seen before! Anyways, he's about 1/4" long and this is all of him.

He doesnt really look dangerous, Im just curious to know what he is:

 

Looks like some kind of arthropod.

 

You can see what look like spines on the sides of it these look like parapodia (22 in total) to me indicating some sort of bristle worm.

 

I thought the same thing last night, but I have never seen a bristleworm behave like that before. Also, when I grabbed this thing, it was shaking like a vibrating cell phone.

 

Looks like a bristle worm

 

It is what is commonly called a "swarmer", which is the reproductive phase used by many polychaete species. Yours appears to be a Syllidae spp that has changed into what you see now. In short, they become nothing more than a swimming "bag" filled with either sperm or eggs and their only purpose is to get their payload up near the surface for water currents to carry their spawn out into the plankton. For more info and photo examples please see the worm section of my hitch hiker pages.

A Hitch Hikers Guide to the Reefs

Chuck