''Arcella hemisphaerica'' is an
amoeboid
An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...
species.
References
Tubulinea
Species described in 1852
{{Amoebozoa-stub