Myxogastria/Myxogastrea (myxogastrids, ICZN) or Myxomycetes (ICN) is a class of slime moulds that contains 5 orders, 14 families, 62 genera, and 888 species. They are colloquially known as the plasmodial or acellular slime moulds.
All species pass through several very different morphologic phases, such as microscopic individual cells, slimy amorphous organisms visible with the naked eye, and conspicuously shaped fruit bodies. Although they are monocellular, they can reach immense widths and weights: in extreme cases they can be up to 1 metre (3 ft 3 in) across and weigh up to 20 kilograms (44 lb).