Slime mold or slime mould is a broad term describing some organisms that use spores to reproduce. Slime molds were formerly classified as fungi but are no longer considered part of this kingdom.
Their common name refers to part of some of these organisms' life cycles where they can appear as gelatinous "slime". This is mostly seen with the myxomycetes, which are the only macroscopic slime molds.
Found in a wide variety of colors, more than 900 species of slime mold occur all over the world and feed on microorganisms that live in any type of dead plant material. They contribute to the decomposition of dead vegetation, and feed on bacteria, yeasts, and fungi. For this reason, these organisms are usually found in soil, lawns, and on the forest floor, commonly on deciduous logs. However, in tropical areas they are also common on inflorescences, fruits and in aerial situations (e.g., in the canopy of trees). In urban areas, they are found on mulch or even in the leaf mold in gutters, and also grow in air conditioners, especially when the drain is blocked. One of the most commonly encountered slime molds is the yellow Physarum polycephalum, found both in nature in forests in temperate zones, as well as in classrooms and laboratories.
Most slime molds are smaller than a few centimeters, but some species may reach sizes of up to several square meters and masses of up to 30 grams.
When food is abundant a slime mold exists as a single-celled organism, but when food is in short supply, slime molds congregate and start moving as a single body. In this state they are sensitive to airborne chemicals and can detect food sources. They can readily change the shape and function of parts and may form stalks that produce fruiting bodies, releasing countless spores, light enough to be carried on the wind or hitch a ride on passing animals.