Plumber’s apprentice Joe Wells touches a mammoth tusk that was uncovered by construction workers in Seattle last week. (Associated Press)

A plumber at a Seattle, Washington, construction site dug up something unexpected last week: a mammoth tusk.

Scientists at the Burke Museum of Natural History and Culture say the fossil dates back at least 20,000 years, when ice swept through the Seattle area.

Paleontologists who began digging out the fossil Thursday said it is 81 / 2 feet long. On Friday, they partly covered it with plaster and prepared to remove it from the site.

Mammoth elephants lived all over the United States and Europe in ancient times, but finding a tusk or any part of those animals is rare, said Jack Horner of the Museum of the Rockies and Montana State University.

“We don’t find them every year or even every five years,” said Horner, one of the nation’s most famous paleontologists.

In most cases, artifacts found at construction sites are destroyed by equipment before anyone even notices them, Horner said.

The fate of this mammoth tusk was up to the construction site owner, who donated it to the Burke Museum.

It’s a relatively rare find and should be preserved for educational reasons, so children will know mammoth elephants once lived in Seattle, Horner said.

“A lot of times, people think these things are worth a lot of money,” he said. Their true value is educational, not what someone can sell a tusk for on eBay, he said.

Scott Koppelman, senior vice president of AMLI Residential, said after contractors found the fossil buried about 25 to 30 feet below street level, the company turned quickly to the museum for assistance.

Discoveries of animal remains from the Ice Age are less common than human remains in western Washington. Preservation of bone and tusks depends on the environmental conditions, such as the water table, the acidity of the soil and how deeply the object was buried, said Allyson Brooks, Washington state’s preservation officer.

“A lot of time, teeth preserve better than other bones,” she said, likening tusks to teeth. She said teeth and tusks are what she and the scientists she works with consider “biological rock.”

Mammoths and mastodons are related and probably roamed the Earth around the same time. Both were very large and hairy. Mammoths and
modern-day elephants are membe­­rs of the same biological family.

Scientists at the Burke believe this tusk came from a Columbian mammoth, which is the Washington state fossil. The tusk is expected to be the largest and most intact mammoth tusk ever found in the Seattle area.

Associated Press