air in a hornwort jar

I noticed something in my jar of hornwort last week. Two rather large bubbles, they really caught my eye. Stuck in the needles of the plant. I guess last time I topped off the jar, some oxygen introduced via the turbulence of water tumbling in through my fingers, trapped the bubbles. They stayed there all week! Like clear beads or jewels, in foliage.

Another thing I've noticed is that for once, the pegged hornwort stems don't weaken at the base and need to be re-tied. I have left this thing pretty much alone since it was set up, just clipping tops when it gets close to the surface, wiping off below the jar rim and topping off with tank water. There's two very small trumpet snails in there now, they seem to keep the algae cleared up. I think the lower parts of the stems stayed healthy because the jar gets light broadside from the window, not just strongest from above. Maybe I will keep this thing going. I kind of like it, and I often get comments on it from visitors to the house.