noun
Placozoa (phylum of simple marine invertebrates)
Taxonomic term for a phylum of very simple, flat, multicellular animals; used in biology and zoology contexts.
平板動物綱は、最も単純な多細胞動物の一群である。
Placozoa is a group of the simplest multicellular animals.
Composed of 平板 (flat plate) + 動物 (animal) + 綱 (class/phylum), a calque of the scientific name Placozoa.