This testate amoeba has contracted its pseudopods inside its shell and remains still.
Commentary by Prof. Yuji Tsukii, Hosei University
The shell surface of the Arcella (testate amoeba) is generally smooth, but in this video, various particles seem to be attached to the surface. Also, the position of the pseudostome (opening) in this organism is not at the exact center of the body. If it were, the organism might be a different kind of testate amoeba other than Arcella.
Sampling Date : 03 July 2009
Sampling Site : Hirose River B Google Map