1) Protozoan 2) Protozoon 
Difflugia is the largest genus of Arcellinida, one of several groups of Tubulinea within the eukaryote supergroup Amoebozoa. Arcellinida species produce shells or tests from mineral particles or biogeonic elements (e.g. diatom frustules) and are thus commonly referred to as testate amoebae or shelled amoebae. Difflugia are particularly common in m...
[n] - a protozoan with an ovoid shell of cemented sand grains
noun a protozoan with an ovoid shell of cemented sand grains
a genus of ameboid protozoans that construct a shell of cemented sand grains.