Researchers have discovered a new species of ancient marine worm, Thanahita distos, from rocks dating to the Silurian Period. The fossil worm comes from a site in western England called the Herefordshire Lagerstätte. Thanahita and the other marine animals found here are fossilized in three dimensions rather than being pancaked like most other invertebrate fossils.
Thanahita, at about 3 cm long (just over one inch), had a tube-shaped body with at least nine pairs of legs ending in one or two tiny claws. Each leg looked like a curving spaghetti noodle, with the two pairs on the neck being smaller than the others. The back of Thanahita was covered in a strange and wonderful pavement of tufts. Each tuft resembled an individual Dahlia bloom and sat atop a low pedestal rising just a few tenths of a milimeter above the surface of the back. The tufts are arranged in a grid, four columns wide, with about four rows of tufts per leg segment running the whole length of the body. Only one specimen is known of Thanahita, and unfortunately its head is missing.
To discover the fine anatomical details of this small soft-bodied worm the team of researchers, led by Derek J. Siveter, had to destroy it. Although it’s exquisitely preserved, it was impossible to remove the fossil from the surrounding rock. Instead, they carefully ground the specimen at 20 μm intervals in the laboratory. After each pass, the ground surface was photographed, and those photographs were digitally combined to create a 3D virtual model of the worm.