I always pop them. I could be wrong, but I figure that if you don't, it will continue to get larger until it pops/breaks on its own and releases even more spores into the tank than if it had been popped when it was smaller.
That would be my guess too... first is Stomatella snail (cute little guys) and the second looks like the Botryocladia sp algae I have in my refugium. I don't know if you should pop them or not... I usually just strap it off with a razor.