English: Temporally alternating life cycles of unicellular holozoans. Life stages of the filasterean Capsaspora owczarzaki. In the trophic proliferative (filopodial) stage, cells are amoebae adhered to the substrate, extending several long, thin actin-based filopodia. These amoebas can detach from the substrate and actively aggregate in the aggregative or ‘multicellular’ stage, producing an extracellular matrix that presumably binds them together. In response to crowding or stress, cells from both the amoeba and the aggregative stages can encyst by retracting the filopodia into a cystic or resistance stage.