Placozoa

 
Pronunciation: /ˌplakəˈzəʊə/

plural noun

Zoology
  • a minor phylum that contains a single minute marine invertebrate (Trichoplax adhaerens), which has a flattened body with two cell layers and is the simplest known metazoan.

Origin:

modern Latin (plural), from Greek plakos 'flat' + zōia 'animals'