Mysterious creature

Hi to all of you aquarium enthusiests.
We are new to the hobby and are totally excited about just everything that comes crawling out of our liferock.
Tonight we bought a small rock just because it looked nice. After we placed it in the tank spines came out of the rock and turned into the most facinating neon colors. The whole thing looks absolutly stunning. In the middle there are two long tentacles. If spooked it will retract comletely back into the rock just like a feather duster. It definetly is no feather duster. Has anybody ever seen or come accross anything like it? I guess it would be a good thing to know if we got yourselfs a good or a bad thing here.
As soon as this beauty will come back out of the rock I will post a picture.
Thanks for your help.

 

this sounds interesting. based on your description the only thing i think it could possible be is a nudibranch but the spikes dont fit.
hi welcome to 3reef

 

I did manage to take pictures, but have not even a clue on how to get them on this site. There are 2 pics in the photo gallery.
I hope that someone out there will be able to identify it, so we will know if it is good or bad.
Thanks to all you guys that have responded so far

 

Here's the pic

 

wow! that looks to be some sort of deep sea creature, i have never seen anything like it!