Micrasterias thomasiana is one of the commoner species of its genus. The approximately circular cells are characterized as being large and flat with a deep incision near the median, which divides each organism into two semicells. The semicells are divided into a polar lobe and two lateral lobes that sometimes are divided again. Micrasterias thomasiana has often been utilized in research and multiplies primarily through asexual means. When this occurs, the cells divide at the nucleus located in the central isthmus and each half produces a new semicell. Thus, each half of the resulting desmid is a different age, and one semicell may be significantly smaller than the other until sufficient growing time has elapsed.