Ancient cultures have long considered opal a special gemstone because of its ability to capture so many different colors. Turns out, that’s not all it can capture: researchers in Australia have identified at least four members of a new dinosaur species whose bones were preserved for 100 million years in opal, the country’s national gemstone.

Australia is a major source of the world’s opal, particularly the black opal found in the town of Lightning Ridge, New South Wales. That’s where miner Bob Foster was working in 1984 when he stumbled on a small, semicircle-shaped bone. Only this wasn’t like the ordinary fish bones Foster had found before in Sheepyard opal field, where he worked. It was vertebrae of a previously unknown dinosaur.

Before long, Foster had found a lot more sparkly, gem-like fossils that were clearly from something unique. And because paleontologists at the Australian Museum in Sydney had asked the public to turn over any dinosaur bones they found, Foster packed the fossils into two suitcases and traveled to the state capital to hand them over.

“I said, ‘I’m the bloke who rang you up, I’ve got two bags of dinosaur bones here,’ and they looked at each other like, ‘Here’s another one’—they get people coming in all the time,” Foster told The New York Times. But then he showed the scientists the distinctive, opal-encrusted fossils. “I opened them and threw the bones all out on the table and they were diving to catch them before they landed on the floor. They changed their approach.”

The museum sent army reservists to excavate more fossils at Lightning Ridge. Yet for a long time, nobody studied them. In fact, Foster later found some of the fossils on display at an opal store in Sydney. He recovered some and donated them to the Australian Opal Center in 2015. After this, other scientists started examining them. On June 3, 2019, they published the first study of Foster’s fossils in the Journal of Vertebrate Paleontology.

The fossils represent at least four members of Fostoria dhimbangunmal, a new species named after Foster as well as the opal field where he found the bones. ‘Dhimbangunmal’ means ‘sheep yard’ in the Indigenous language of the Yuwaalaraay, Yuwaalayaay and Gamilaraay peoples near Lightning Ridge. Foster’s wife Jenny, who is Gamilaraay Aboriginal, chose the name to honor them.

The F. dhimbangunmal was a herbivore with a horse-shaped skull who lived during the mid-Cretaceous period, when Lightning Ridge was a floodplain rich in vegetation. The specific dinosaurs Foster found were mostly juveniles, with one probable adult stretching 16 feet in length.

These fossils constitute the first herd or family group discovered in Australia, as well as the largest known collection of dino fossils preserved in opal. Dinosaur discoveries are rare in Australia compared to those in northern continents like Asia and North America, but paleontologists believe we may discover many more in the future.

In 2018, the same scientists who identified F. dhimbangunmal announced they’d found another new species, the Weewarrasaurus pobeni, about 25 miles southwest of Lightning Ridge. Like the fossils Foster discovered at Sheepyard, the lower jaw of the W. pobeni was preserved in sparkling opal.