Sphaeroforma arctica, is a unicellular eukaryote with a pivotal position in the tree of life.
Sphaeroforma is a member of the Ichthyosporea clade, which is the earliest branching holozoan lineage.
Cellularization involves coordinated inward plasma membrane invaginations dependent on an actomyosin network that leads to the formation of a polarized layer of cells resembling an epithelium.
This process is associated with tightly regulated transcriptional activation of genes involved in cell adhesion.
Taken together, Sphaeroforma arctica is a great model organism from both evolutionary and cell biology perspectives.