Trichoplax adhaerens (tp) is the only living species in the phylum placozoa. individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). there are four types of cells, none of which is a nerve or muscle cell, and none of which has a cell wall. they move using cilia, and any "edge" can lead. tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.