This is the story of a man who had a tapeworm living in his brain for at least four years. You can see the worm moving from one side of his brain to the other in this series of images, taken over that timespan:

This 50-year-old man came to the hospital complaining of headaches, weird smells, seizures, and memory problems. Eventually, Tim Chester of Mashable reports, the doctors did brain surgery, found the tapeworm, and removed it.

Now, how did this person get a tapeworm in his brain? It's because it wasn't any ordinary tapeworm. Ordinary tapeworms live in stomachs, and you can find them in dogs and cats in the United States because fleas can carry tapeworm larvae.

This brain tapeworm is a very rare and different species, called Spirometra erinaceieuropaei. It lives in some Asian countries (this patient had recently been to China) and can be acquired through eating undercooked frog meat or drinking contaminated water.

Scientists later sequenced its genome — the first of this species. They hope to find clues in its DNA of what kinds of drugs will best fight it in the future. They published this tale, and its scientific results, in the journal Genome Biology on November 21, 2014.

Here's some more crazy things you can see with MRI: