Some caterpillars aren’t what they seem—because they’re not caterpillars at all.

The green-banded broodsac is a parasitic flatworm that invades a snail’s body and performs one of nature’s strangest makeovers. Once inside, it crawls into the snail’s eye stalks, inflating them into colorful, pulsating tubes that look exactly like juicy caterpillars.

Then it rewires the snail’s behavior—forcing it to crawl into the open, where birds are more likely to spot it.

A bird snaps up the fake "caterpillar," eats the parasite, and becomes its next host. The cycle continues.

This isn’t just metamorphosis—it’s biological puppetry, complete with costume and choreography.