All animals develop from a single-celled zygote and undergo complex morphogenetic processes to form multicellular organisms. These processes are regulated by intrinsic and extrinsic factors that drive key developmental events, such as symmetry breaking, cell division, and differentiation. Despite the remarkable conservation of these pathways across species, the evolutionary origins of these morphogenetic mechanisms remain unclear. A major challenge in addressing this question is the limited availability of microscopy and cell biological data from key protists that occupy pivotal phylogenetic positions in the eukaryotic tree, including those identified as the closest unicellular relatives of animals. In this talk, I will present how our lab is utilizing Expansion Microscopy to capture novel ultrastructural details of microbial life cycles. I will also share recent insights into Ichthyosporeans, a lineage of protists closely related to animals, which exhibit diverse multicellular development strategies. These include species that undergo coenocytic development followed by cellularization, as well as others that develop through cleavage divisions to form spatially organized multicellular colonies. Our findings highlight the importance of studying diverse unicellular taxa to trace the origins of animal multicellularity, positioning Ichthyosporeans as a promising model for exploring the evolutionary roots of animal embryogenesis.