This is the first larval stage in any digenetic trematode life cycle. This miracidium of Schistosoma mansoni is short-lived (24 hours), non-feeding, and seeks out a specific snail of the genus Biomphalaria spp.  It is ciliated with the anterior end to the right.  The blue mass toward the anterior end is a collection of penetration glands which release enzymes that digest a pathway into the specific host snail.  The larger mass toward the posterior end is the germ ball which carries the germ line for the polyembryonic development typical of trematodes.  400x