I'm seeing more and more of these on my plant leaves and I'm wondering what they are. The stuff looks like brown (sometimes transparent) flat bubbles that stick on the leaves. They can be removed by hand (and they have a "crispy" feeling). They do not look like regular snail eggs (transparent gel + white eggs). They attach on all kinds of plants (hygrophilia, anubia nana, cryp, ludwigia, alternanthera). It started maybe two or three weeks ago (I could see only one) and in the past few days, I've seen more and more (let's say ~10).
Aquarium population: 9 neons, 8 lampeyes, 7 panda cories, 2 blue rams, 5 black phantoms (just introduced two days ago, one died yesterday...), snails (mostly pond snail and ramshorn snails).
This is a 41 gal NPT (lots of plants, potting soil + gravel).
Could it be some sort of algae? Or fish eggs?
I've included some pictures (sorry for the food lying around, I took the picture during feeding time). The brown spots are right in the middle of the pictures.