Is this goniapora or alvapora

[MoshJosh]

The white one in the back?

 

[OrchidMiss]

Alveopora have 12 tentacles on each polyp while Goniopora have 24.
That's usually the easiest way to answer that question. I'd say those are both alveopora.

 

[AFHokie]

Alveopora. Gonis have 24 tentacles, alveos 12.

 

[Sean Clark]

I was going to say count the tentacles but I was beaten to it.

 

[tbrown]

Could also be a Bernadapora (sp?) If it has more than 12 but less than 24. I'm counting 16-18 on the some but it's really hard to tell with the glow.