Some type of rotifer?

In trying to isolate Trebouxia from an Evernia lichen. I found that some of the cultures are contaminated by a what I think are rotifers. I am not sure of what kind of rotifer (or other organism) is the one pictured, so if anyone has some idea please let me know.

I also recorded a video of what I think are belloid rotifers feeding on the same lichen culture:

https://peertube.uno/w/uoSCNagVVmbuMcgXdVfPGR

I don't have much hope that the algae will survive this attack, but I might turn those jars into rotifer cultures.