The sheath is known to contain actin , which might be involved in migration. These usually are brightly coloured. Figure C shows the small fruiting structures of Physarum cinereum on a grass leaf. This species is quite commonly seen as grey patches on lawns in damp conditions, but it uses the grass blades merely as a 'perch' on which to fruit, and it can simply be brushed off the lawn. Figures D and E show two stages in the fruiting of Lycogala epidendrum , a common species on rotten wood.
E is the final stage, where the sporangia have matured and turned grey.
They release small grey-coloured spores by rupture of the sporangial coat. These two cell types can interconvert. The myxamoebae can multiply to large numbers, but in many slime moulds they will not produce plasmodia unless two myxamoebae of different mating types fuse with one another. Thus, the myxamoebae seem to be haploid, and the plasmodial stage is diploid. The myxomycota are not specially important or notable for their activities in natural environments, but their peculiar behaviour has made them important as model systems for experimental studies on topics such as the cell cycle, morphogenesis and chemotaxis.