Microscope ID Dinos? Diatoms?

[Bfishing]

Hey guys! These little creatures have been terrorizing my sand bed for months with ugly brown rust mats and then disappearing at night. No fish or snail deaths. Any idea of what they could be? They seem to form little cluster colonies as well and glide around. This is the closest I could get my microscope to go unfortunately. I’m guessing sand dwelling dinos but was wondering if anyone thought any different. My previous thread has some more info as well!

 

[Bfishing]

Some photos too if the video acts up