Slime molds or slime moulds are a variety of small or microscopic organisms in different groups. They have both single-celled and multicellular forms during their life cycle, the individual cells coming together to form fruiting bodies that produce spores. Most live in damp places such as rotting wood.
More formally, the slime molds are a polyphyletic assemblage of distantly related eukaryotic organisms in the Stramenopiles, Rhizaria, Discoba, Amoebozoa and Holomycota clades. Most are near-microscopic; those in the Myxogastria form larger plasmodial slime molds visible to the naked eye. Spores are often produced in macroscopic multicellular or multinucleate fruiting bodies formed through aggregation or fusion; aggregation is driven by chemical signals called acrasins. Slime molds contribute to the decomposition of dead vegetation; some are parasitic.