Bubble Coral or Bubble Algae?

[Phyl]

I got this mostly dead piece of bubble coral from someone who was breaking down his tank (he threw it in the box with some other frags I was taking). The thing has been trying to open since I had it but it isn't doing so great. Then yesterday I noticed what I hope is new bubbles, but I have the sneaking suspicion that what's on this rock is actually bubble algae, not bubble coral.

TIA

[Fluff]

Looks like bubble algae to me. Never seen a bubble coral quite so green.

[XXFirefighter]

bubble algae all the way !