Microgromia haeckeliana is the most common species of the genus Microgromia in Simmelried. It occurs there frequently and regularly. As with almost all other small testate amoebae, the individuals are not found directly in the samples because they are often stuck in detritus flocs. However, if an aliquot of the sample is transferred into Petri dish and some floating coverslips are placed on the surface, Microgromia haeckeliana (and many other testate amoebae) will settle on it after only a few days.

Microgromia haeckeliana has a septum at the base of the neck, like all other Microgromia species. The short neck of Microgromia haeckeliana is oriented in a straight or oblique way to the shell and sometimes it is thickened at the distal margin (s. figs. 4 and 5). Although de Sadeleer drew and described specimens with two septa (s. drawings above), I could only observe specimens with one septum in my population. Another characteristic peculiarity of Microgromia haeckeliana is the accumulation of iron precipitates on the shell (iron oxide and iron hydroxide). This causes the shells to turn more and more orange or brown with age (s. fig. 7). In extreme cases the layer of iron precipitates can be so thick that the neck disappears in it (s. fig. 8).