What is this bubble on my frogspawn?

[Merv49]

For the past few months this bubble has been on my frogspawn. Just wondering what it might be.

 

[James M]

It’s going to split , I thinks it’s called a growth bubble

 

[Shefilbel7]

For the past few months this bubble has been on my frogspawn. Just wondering what it might be.

Agree with the comment above. Mine will do that before they split sometimes too