bubbles in splotches on my glass

[reefer newby]

I have a splotch about four inches round on my glass.it appears to have air bubbles in it. Can't download a pic , unfortunately. The splotch itself is almost clear. Any ideas without seeing?

 

[SirKevinD]

Maybe snail eggs?

 

[Reefing Madness]

Spot of algae growth. Wipe it off.