What is this cool little thing?!?!?

[sirbrently]

Never seen anything like this before.. Ive been watching this thing grow now for a couple months... At first when is was very small I thought it was a ricordea.. But, I am starting to think differently now!
Pictures are under LED's i'll try and get something more clear-- was using my phone!

 

[saban2013]

Looks like some type of anemone. With the picture you have, it is hard to say what species, but it is an anemone.

 

[seaony]

I had some of these pop up in my aquarium. Mine turned out to be plate corals. If you can touch the tentacles and they shrivel up revealing a hard skeleton, I'll bet they are plates. Mine were amber gel with neon green tentacles.

 

[bang guy]

Looks like some type of ahermatypic LPS coral based on the stinging balls on the ends of the tentacles. Related to Phyllangia sp. perhaps.
Have you tried feeding it?