Hey. Hope you don't mind me posting a couple of vids in your thread, it seemed like the best fit. But I'd be happy to remove if you prefer. Was wondering if you'd seen anything similar?
Pruning some kenya tree, looked at a drop squeezed out from it. Lots of round brown zooxanthellae. But also surprised to find smaller, less pigmented, irregular shaped, rapidly wiggling spinning things in the sample too. They seemed to glob up and accumulate other material nearby.
I googled images of the motile phase of symbiodinium, but they have the same pigmentation and approximate size as the others. Didn't seem a match.
medium power
https://youtu.be/WunSk22PK94
higher power
https://youtu.be/bkH76hE0Bc4
I also saw the same thing from pulsing xenia sample.