For hundreds of years, biologists knew of the giant shipworm only from shell fragments and a handful of dead specimens. Those specimens, despite being preserved in museum jars, had gone to mush. Still, the shipworm's scattered remains made an outsized impression on biologists. Its 1m-long tubular shells - the shipworm isn't technically a worm but a bivalve - were so striking that Swedish taxonomist Carl Linnaeus included the animal in his book that introduced the scientific naming system "Systema Naturae". And yet no one could get their hands on a living example of the giant shipworm, or Kuphus polythalamia. Unlike with other shipworms, named because they ate their way into the sides of wooden boats, no one knew where the giant shipworm lived. "It's sort of the unicorn of mollusks," Margo Haygood, a marine microbiologist at the University of Utah, told the Washington Post. The habitat of the world's longest clam is a mystery no longer. As Haygood and her colleagues reported this week in the Proceedings of the National Academy of Sciences, the search for the giant shipworm has come to an end. Television news in the Philippines dealt the mortal blow to the shipworm's near-mythical status. A TV station aired a short documentary segment about strange shellfish living in a lagoon. The show filmed the mollusks growing in the muck, as though someone had planted rows of elephant tusks. As luck would have it, a colleague of Haygood's in the Philippines caught wind of the segment. Researchers investigated the lagoon, where they plucked a live shipworm from the mud, slipped it along with some seawater into a PVC pipe and shipped the animal to a laboratory. "I've been studying shipworms since 1989 and in all that time I had never seen a living specimen of Kuphus polythalamia," Daniel Distel, a co-author of the new study and the director of Northeastern University's Ocean Genome Legacy Centre, wrote in an email. "It was pretty spectacular to lift that tube out of its container for the first time." Distel carefully chipped away at the giant shipworm's massive shell. Smaller shipworms are fleshy pink, beige or white, as are most clams. Not the giant shipworm. Its body is black. "To see this giant gunmetal black specimen was amazing," Distel said. "On the one hand I was pretty excited to see what it looked like inside. On the other hand it was a little intimidating to dissect this incredibly rare specimen." A full-grown giant shipworm reaches up to 1m-long, which means that when draped across the width of a twin bed, the clam would just barely fit. "It's quite heavy. It's like picking up a tree branch or something even heavier," Haygood said. "The living animal is just magnificent." What's more, the giant shipworm barely has a digestive system. "It's not feeding in any normal way," Haygood said. The clam has a mouth and a small stomach, but its gills are supersize. Living within those gills are bacteria. That's not unusual for shipworms: The clams, as a rule, have symbiotic relationships with microbes. Usually, though, the microbes help shipworms digest wood.