I've seen Spirostomum group together before, but never like this. This clump was huge, very visible on the slide. The first picture is the 40X Plan Achro, the second is a 20X Plan Achro, just to prove they are actually spirostomum. Both are brightfield. I tried using my halogen light to illuminate the top of the clump, but it had no real effect.
Canon 50D, Photolense.
Don