A multicellular form has recently been described.

That is not all: the multicellular form loses its cell walls, and becomes a syncytium.

Abiogenesis already in a multicellular form?

I suppose that could be addressed by single cell organisms evolving from multicellular forms.

The ability of an organism to switch between unicellular and multicellular forms is not unique to Dictyostelium; myxobacteria, yeasts and sponges can do something similar.

The evolution of multicellular forms brought about selective pressures for ever-increasing sophistication to innate immune systems.

This implies that the Placozoa would have arisen relatively soon after the evolutionary transition from unicellular to multicellular forms.

Life developed from prokaryotes into eukaryotes and multicellular forms.

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms.

An example is Candida albicans, which, when it infects host tissue, switches from the usual unicellular yeast-like form into an invasive, multicellular filamentous form.