I have found this very large (single celled) ciliate several times, always in moss samples, from day 2 or 3 to ~10. The largest individuals are >300µm (easily visible to the naked eye, larger than most tardigrades), with some around 150-200µm and many smaller ones. They form digestive cysts after which they emerge larger and empty, but I never witnessed any reproduction. They appear to be predatory and cannibalistic, zipping around like roombas trying to feed on each other and everything else that fits into the huge oral fold on the ventral side, mostly smaller colpodans. Under the stereo microcope (which is all I have atm) and with lateral light they look really beautifully plastic and fascinating, but hard to capture.

I suspect it to be bresslaua vorax based on their enormous size and different size categories, but i'm in no way an expert, please give an opinion. My first guess was colpoda magna, based on size and general shape