Closest living relatives of animals are
Choanoflagellates unicellular and colonial flagellated protists occupy sister lineage to Metazoa within opisthokont supergroup, diverging most recently compared to green algae belonging to Archaeplastida, amoebae within Amoebozoa or ciliates within SAR. Ultrastructural and genomic evidence includes homologous collar of microvilli surrounding flagellum, receptor tyrosine kinases, cadherin repeats, Myc oncogenes and mitochondrial gene synteny. Genera Monosiga, Salpingoeca and colonial Proterospongia demonstrate rosette formation resembling sponge morula. Therefore phylogeny positions choanoflage
Ref: Campbell Biology 12th ed. Chapter 28 Protists Close to Animals; Nature Scientific Reports Choanoflagellates sister to Metazoa