A small ciliate with relatively long cilia and cirri is randomly bouncing around between particles. When viewed from above, it appears round, but from the side it looks like a turtle.
Commentary by Prof. Yuji Tsukii, Hosei University This organism is Aspidisca. Vertical lines along the back of the body suggest that it is Aspidisca cicada (former name: A. costata). It can be found in many kinds of soil.
First we see a small ciliate, Aspidisca, passing through a space surrounded by particles. Then a large slender ciliate appears and begins to look for food. We can see a small ciliate in the process of division beside one of the particles.
Commentary by Prof. Yuji Tsukii, Hosei University The organism approaching from the lower right may be Aspidisca cicada
(previously called Aspidisca costata).