Miracidium

noun

1. A ciliated larva of a digenetic trematode, which hatches from the egg and enters the first intermediate host, where it develops into a sporocyst or a redia.
2. The free-swimming larva of the liver-fluke. The body is ciliated and the larva swims about seeking for a definite mollusk, its future host, into which it bores its way by means of the snout, which, in certain species, is armed with a stylet.
3. A free-living motile form of a trematode, covered with cilia, which settles in the mollusc to become a sporocyst.