Live coral?
 

I can't get a good picture. One piece of life rock in my tank is has a coral texture and what looks like green polyps. Is this live coral? The reason I'm asking is this piece of rock is on the very bottom of my aquascaping and I was wondering if it was something worth moving to the top to get it in light. It would mean having to re stack most the rock in my tank to do so.

http://i274.photobucket.com/albums/j..._F/rock006.jpg

It looks like sponge to me. Live, but not coral.

it is 2 x 1 inch and hard to the touch. The white ridges are "rock".

You can try...but it is also a big assumption that it is a Xoanthellae coral. Not all corals can live on light.

Many coral skeletons take on a greenish tinge after all the flesh has decomposed or been eaten. They go green, then brown, then coralline can take over. The coloration is from different strains of bacteria. My buddy gave me his lobopyhlia skeleton and a hammer skeleton, and both had same color.

if it were alive but without zooxanthellea it would be whitish and flesh still visable.

Thanks - this explains things perfectly. I guessed they were skeletons but couldn't figure out why they were such an intense green inside with no algae on the outside.

What about pink / blue sponges? Are they photosynthic?

And by photosynthetic I mean 'have symbiotic photosynthetic algae'