Have I been touched by his noodly appendage? The Flying Spaghetti Monster has appeared to me as a mass of writhing cercariae!
These are cercariae of the trematode species Renicola buchanani. These cercariae have recently emerged from their snail host, and have joined their tails together to form what is sometimes called a “rat king.” By joining together in a writhing ball, the parasites grab the attention of their fish hosts. Apparently this rat king looks delicious, because the fish consume the parasites and become infected. The parasites travel to the fish’s liver, where they stay until their fish host is eaten by a predatory bird.