Testate amoebae

Testate Amoebae (Rhizopods, Thecamoebians) are single-celled protists partially enclosed in a test (shell).

They are commonly found in soils, leaf litter, peat bogs and near/in fresh water.

Almost all testate amoebae reproduce asexually. Testate amoebae move by using pseudopodia (false feet), a temporary cell extension used for moving, and taking in food.

Testate amoebae taxa are differentiated by their test characteristics and what kind of pseudopodia they have (lobose, recticulose, or filose).

Test/shell
Tests can be made from secretion or agglutination, or sometimes a combination of both. Past environmental changes can be determined from analysing the composition of fossil tests, including the reconstruction of past climate change.

Evolutionary history
Fossils of testate amoebae date back to the Cryogenian period. Testate amoebae are theorized to be mostly polyphyletic (coming from more than one ancestral type), but testaceafilosea, another group of testate amoebae, are theorized to be made up of one ancestral type (monophyletic).