What is this White Sac?

[Dan1979e]

Can anyone help me Unwhat this white clearing sac that appeared on my Hammer last night? I peaked in on my before bed to find this sac that is about the size 1”-1”2 It’s the oddest thing I’ve seen just appear in my tank ever!

 

[exnisstech]

@ISpeakForTheSeas ?

 

[ISpeakForTheSeas]

I haven't looked too much into it, but- as mentioned in the other threads - this seems to sometimes indicate splitting, and other times it just bubbles for a while and goes back to normal; nobody seems quite sure as to why it happens though:
https://www.reef2reef.com/threads/what-is-this-white-sac.1047674/https://www.reef2reef.com/threads/what-is-this-white-sac.1047676/