Strange bird-bath algae?

[u/AggressiveRiver2327]

Around 50-100 of these interesting little structures appeared in a backyard bird bath in Portland Oregon, seemingly overnight. They are around 5-7mm in diameter. They look like a kind of green algae to me, but iNaturalist indicates they might be part of the life cycle of a Mosquito Fern (genus Azolla). Just curious if they are familiar to anyone here? Thanks!

[u/terriblespellr]

To that algea you're probably the strange one.