New research from the Wellcome Trust Sanger Institute found that a tapeworm lived inside a man's head — near his brain — for four years.The parasite, Spirometra erinaceieuropaei, had an "incredibly long genome," Discovery News reports. The large genome has 1.26 billion base pairs, making it 10 times longer than other tapeworm genomes, and one-third the size of a human genome.The centimeter-long tapeworm was removed via surgery, but not before it traveled two inches into the head of the Chinese man, who was living in the U.K.