Just to share....
My so so Red Tree Sponge Coral (I stand to be corrected) - photo by iPhone
2 observations:
1. This sponge coral is really like a sponge, it can grow twice it's size and also contract to it's original size at different times.
2. The "white flowers" that appear on the branches do retract if touched. Looks like a cactus.
If anyone has another observations, please do share...