Bubble on Bird of paradise?

[DukeD]

Hi everyone. New to the forums here (and to the hobby)!

Had a question about this coral.. tank has been up for bit over 6 months. I added this Bird of paradise frag pretty early on, so it's been in my tank for about half year now.

Wondering what this bubble is on the frag? It looks to have some color (more visible in blue light) and zooxanthellae on it? Thanks!

 

[Saltyreef]

Corals seem to do this from time to time. They call it a cyst or bouncing. It may go away but cool if it stays.

Ive seldom seen this on small polyp stoney corals, but once saw a bounced chalice.

 

[Cichlid Dad]

Possibly an egg sack. What is your stocking including all clean up crew

 

[DukeD]

Thanks.
The cyst makes sense. The bubble has been there for months, so unlikely to be an egg sack.. also only have a couple clowns, hermits, and standard snails.

 

[Dburr1014]

Bird of paradise bounce.
Frag it and make $$$!