The answer is phylum Sarcodina and class Heliozoa.
Actionophryx belongs to the group of Sarcodina. However, this is an older classification, and it is known that it belong to the groups of amoebas. It has a spherical body (helios, greek for sun) with axopodia (arms) so it is classified to the class sun-animalcules or Heliozoa. The body is surrounded by a glassy silica shell. It lives in freshwater, but some species are found in seas and oceans.
