Trichosphaerium
Trichosphaerium is a genus of amoebozoan protists that present extraordinary morphological transformations, both in size and shape, during their life cycle. They can present a test that may or may not be covered in spicules. They are related to the family Microcoryciidae, which contains other amoebae with tests, within the clade Corycidia of the phylum Amoebozoa.
Morphology
Trichosphaerium is a genus of amoebae characterized from other Amoebozoa by a multiporous test and a specialized non-motile pseudopodium, known as a dactylopodium, shaped like a digit. The dactylopodium is considered a sensory structure. Its morphology, behavior and life cycle are extraordinary in comparison with other protists. During its poorly understood life cycle, Trichosphaerium undergoes dramatic changes in shape and size. They can grow from as small as 10 μm to giant cell sizes of over 1 mm, observable by the naked eye. They can display such varied recognizable morphotypes that they can be easily mistaken with other species of amoebae.Controversial reports describe an alternation of two trophozoite stages within its life cycle: the "schizont", an amoeba surrounded by a test covered in flexible spicules, and the "gamont", an amoeba surrounded by a more flexible and fibrous test without spicules. According to studies written by German protozoologist Fritz Schaudinn in 1899, the gamont stage produces flagellated gametes, which fuse into a zygote to generate the schizont stage. Although both morphotypes have been observed and kept in laboratory cultures over the decades, this alternation of generations has never been observed in them, which adds a layer of complexity to the unusual, poorly understood behavior of these amoebae.