The find comes from Yunnan, China, where a sedimentary rock layer called the Wulongqing Formation is chock full of tiny fossil brachiopods of a species named (quite sensibly) Neobolus wulongqingensis. Back in the Cambrian Period, shortly after multicellular animal life bloomed into incredible variety, these creatures were living on the seafloor. A team led by Zhifei Zhang at China’s Northwest University discovered that N. wulongqingensis was not alone in the rock—many were adorned with whitish tubes on the exteriors of their shells…
Specifically, the researchers say they look like an example of what’s known as “kleptoparasitism,” meaning they pilfered the brachiopod’s lunch. Brachiopods are filter feeders, sucking in water and catching food particles caught in the stream. By extending just beyond the brachiopod’s open shell, the tube parasites could catch food on its way in. It would be a bit like strapping yourself to the nose of a baleen whale and holding a net in front of its mouth. You’d get free food, and the whale would get less nourishment for the effort expended.Scott K. Johnson, “Incredible fossil find is the oldest known parasite” at ArsTechnica
Paper. (open access)
Curiously, researchers are pretty sure it was a parasite but what it is, apart from that, remains elusive:
“This looks like it is a host-parasitic relationship,” says Xiaoya Ma at Yunnan University in Kunming, China, who has previously found evidence of Cambrian parasitism. She says the huge number of animals studied makes the finding “very sound”.
“We also found that the orientation of the tubes all seemed to be consistent,” says Strotz. “The alignment of the tube preferentially aligns with the feeding intake of the brachiopods.” This suggests the worm-like creatures were “kleptoparasites” that stole the brachiopods’ food as it was sucked in by their tentacles.
Strotz also argues that they were obligate parasites, meaning they couldn’t survive without their hosts, but Ma says there isn’t enough evidence. “We don’t know what this tube-dwelling organism is,” says Ma.Michael Marshall, “Oldest known parasite is a worm-like animal from 512 million years ago” at New Scientist
It’s an unusual case of knowing more about the organism’s behavior than about the organism itself.