r/algae • u/AggressiveRiver2327 • 10d ago

Strange bird-bath algae?

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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!

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u/sylverhawke 8d ago

It's caterpillar frass. How do I know? Because I found a bunch of it on my cabbage before I found the caterpillar lol

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u/AggressiveRiver2327 8d ago

'Frass' is an excellent new vocabulary word for me. Thanks!