Polyembryony is a form of cloning of intermediate stages.
1 ciliated miracidium will enter a snail
Miracidium differentiates into a non-feeding mother sporocyst.
Mother sporocyst has embryonic tissue which produces either feeding redia or another generation of non-feeding daughter sporocysts.
Redia/daughter sporocysts have embryonic tissue which produces cercariae, which emerge from the snail.
Cercariae may burrow directly into definitive host, as in Schistosoma spp., or they may form another “resting” larval stage, a metacercaria on a 2nd intermediate host.