Acrasiomycetes -

: They exist as individual, independent amoebas. When food runs out, they swarm together to build a multicellular fruiting body called a sorocarp. Even when tightly packed together to move or build this structure, they remain separate cells with their own individual cell walls or membranes.

If you are studying Acrasiomycetes, these are the core biological characteristics that define them: acrasiomycetes

To understand why Acrasiomycetes do not form a solid or continuous piece, it is helpful to look at how they compare to "true" slime molds: : They exist as individual, independent amoebas