Ammonia tepida is a benthic foraminifer living in the sediment of brackish waters.

It is very similar to Ammonia beccarii, but the latter lives on the surface of red algae.

[2] Once considered a globally widespread taxon, a recent genetic and morphological study has revealed that many of what were once considered members of A. tepida in fact represent other species of Ammonia, primarily Ammonia veneta, with true specimens of A. tepida only being found in Atlantic waters, off the coast of the Americas.

It is able to tolerate a wide range of temperatures and degrees of salinity, as well as to survive severe environmental conditions.

[5] Laboratory experiments showed that it may also prey on small animals, such as nematodes, copepods and mollusk larvae.