Multicellular organisms having less-specialized cells than in the Metazoa; comprises the single phylum Porifera WordNet 3.0 & Open English WordNet

Parazoa are a taxon with sub-kingdom category that is located at the base of the phylogenetic tree of the animal kingdom in opposition to the sub-kingdom Eumetazoa; groups together the most primitive forms, characterized by not having proper tissues or that, in any case, these tissues are only partially differentiated. Wikipedia