[1] It constitutes a plankton community and is found throughout the year, most abundantly in spring and fall, in coastal areas.

The unusual autotrophic property was discovered in 2006 when genetic sequencing revealed that the photosynthesising organelles, plastids, were derived from the ciliate's principal food, the autotrophic algae called cryptomonads (or cryptophytes), which contain endosymbiont red algae whose internal chloroplasts (evolved via endosymbiosis with cyanobacteria) indirectly enable M. rubrum to photosynthesize using sunlight.

[6] Moreover, these “stolen” plastids can be further transferred to additional hosts, as seen in the case of predation of M. rubrum by dinoflagellate planktons of the genus Dinophysis.

[7][8] In 2009, a new species of Gram-negative bacteria called Maritalea myrionectae was discovered from a cell culture of M.

Genetic analysis showed that in the American coastal areas, the primary food of M. rubrum is the algae most closely related to the free-living Geminigera cryophila.

In order for the plastids to be normally active, they still require enzymes, which are synthesised by the sequestered algal nuclei.