[4] A freshwater flagellate of similar morphology used to be included in this genus as Trimastix pyriformis,[5] but was moved to Paratrimastix in 2015.
He described the genus at the time as free-swimming naked animalcules that are oval, or pear shaped, with a membranous border and three flagella inserted on the anterior end.
[7] Current research indicates that despite there being no evidence that the organelle can produce ATP, there are certain mitochondrial functions that it appears to have maintained.
[3] In order to maintain an anoxic environment without parasitism or endosymbiosis, Trimastix are most often found inside the tissues of dead and decaying marine vegetation.
[3] Trimastix species do not have typical aerobic mitochondria, but they do have remnants of an ancestral mitochondrion, in the form of a hydrogenosome- or mitosome-like organelle.