Unresolved Copepods or Parasites???

So I was relaxing taking a look at my first coral, a small colony of zoanthids. I noticed this little white thing walking around on the zoa's and my first reaction was it had to be a copepod because I didn't dip my coral. I watched him but he disapeared quickly because they are so dang small. I kept on watching and I noticed a bit of a bigger insect. It looked like a copepod but a tad bit bigger. It wasn't white, but it almost had a brown tint to it. I don't think it is a worm, because of the fact that it was walking around. The white bug was much more active crawling on and off the frag, while the brownish one wasn't active much at all sitting under the polyps. Please help me out. What in the world is this thing, If they are copepods, are these beneficial to my tank? Thanks Alot!

 

Hitch Hiking Copepods, Isopods and Amphipods

The link above will help you with the ID.

Parasites that you can see with out assist of a microscope are not common. They do exist but the is usually flukes, Criolanids....

Most are harmless Zooplankton.

 

does it look like a mini slug with frills along its back?

 

kind of like :

kind of, not exactly like this

 

Be very carefully, there are zoa rating naudi's.