Light micrograph of Physarum sp. slime mould fruiting bodies, or sporocarp. Plasmodial slime moulds are enormous single cells with thousands of nuclei. They are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm (called a plasmodium) with many diploid nuclei. Individual plasmodium may coalesce to form larger plasmodium. As the larger plasmodium move around they feed on bacteria, algae and fungal cells. Eventually the plasmodial protoplasm becomes concentrated into a number of small mounds (sporangial initials) which then proceed to develop into sporangia.