Scientists at UC Riverside asked users of the social media site Reddit for help coming up with possible explanations for a series of bizarre, circular fossils found on an ancient seabed.
The researchers received dozens of submissions and two were deemed most plausible, netting each of their authors a cash prize of $200.
UC Riverside's Nigel Hughes first encountered these ring fossils in Wisconsin in 1986. Amateur paleontologists Jerry Gunderson and Ronald Meyershowed him the specimen and he was immediately intrigued.
“They are so sharply defined and so striking,” he said. "What could possibly be the explanation for that?"
The impressions are 490 million years old, from a time when that part of Wisconsin was covered in shallow ocean water.
It was a rich time for animals and many creatures lived in these marine habitats, Hughes explained.
“It’s a totally different world than the world today,” he said.
Hughes never came up with a satisfactory explanation for the rings, so he filed them away for later.
Jump to earlier this year. Hughes thought the power of the Internet might give him a fresh take on this ancient mystery.
He created a webpage and a video and started prompting people for their thoughts on these fossils.
Oh, and to help motivate the hive mind, Hughes and his team offered a cash prize of $500.
Answers started pouring in on the contest's Reddit page. The site logged over 70 responses.
Some were tongue in cheek, suggesting the rings were related to crop circles or are the stains left by prehistoric coffee mugs.
But some submitters gave detailed explanations, complete with pictures and scientific references. Some thought bubbles may have caused the rings, others attributed them to jellyfish.
Two teams suggested a similar idea involving the egg casings of snails.
"Certain snails build a kind of cone like structure that extends up above the sea floor, but does intrude a little bit down into it," Hughes said.
This explanation is based on a modern variety of moon snail, but Hughes said it's plausible a similar snail existed back when these fossils formed.
It would help explain why these rings tend not overlap, he noted.
Another submitter suggested that a sea sponge created the marks as it glommed onto the ocean floor.
Both of these suggestions sparked new lines of inquiry for the UC Riverside researchers, so both won the contest.
They increased the pot to $600 and gave each submitter a third of the prize.
Hughes said this crowd-sourced experiment was a success and in line with the spirit of his original encounter with the rings.
After all, it was a pair of amateurs in Wisconsin who brought the interesting fossil to his attention.
“Paleontology is still a science in which amateurs can make a very real and vital contribution,” he said.