marks precursors of somatic lineages and is required for germline formation in the sea anemone .

In animals, stem cell populations of varying potency facilitate regeneration and tissue homeostasis. Notably, germline stem cells in both vertebrates and invertebrates express highly conserved RNA binding proteins, such as , , and . In highly regenerative animals, these genes are also expressed in somatic stem cells, which led to the proposal that they had an ancestral role in all stem cells.