All moral rights asserted. Recolouring or alteration of the image is prohibited without permission. Coloured scanning electron micrograph (SEM) of the social amoeba, or slime mould, Dictyostelium discoideum forming an aggregation. Amoebas are moving towards centre right from all directions. Bacteria (blue) are also seen. Under favourable conditions, D. discoideum lives as a unicellular organism in the soil. When there is a lack of nutrients, the unicellular amoeba form a multicellular aggregation known as a slug. The cells within the slug differentiate, with some forming a fruiting body, or sorocarp, on a long stalk, which releases spores when mature. D. discoideum is being researched for use as a unicellular 'factory' to produce a number of molecules including antibiotics and olivetolic acid, a precursor of tetrahydrocannabinol (THC), the psychoactive substance in cannabis. Magnification: x350 when printed at 15 centimetres wide.