GLEN ELLYN, Ill. — It skipped tolls. It had a Twitter hashtag and a GPS tracker. It even posed for photos with groupies.

The 50-foot-wide, 15-ton electromagnet attracted a sensation wherever it went during its slow, delicate 3,200-mile journey from New York to suburban Chicago. The land-and-sea trip culminated when scientists threw a rock star’s welcome for the mysterious, shrink-wrapped cargo on Friday as it arrived at the Fermi National Accelerator Laboratory to help study blazing-fast particles.

“’Oh look, they found a flying saucer!’” retired software developer Chris Otis recalled thinking when he saw the massive, disc-shaped device when it made a pit-stop in a Costco parking lot.

Otis used his cellphone to take photos as he and others marveling the contraption wondered what would happen if it suddenly went live.

“I figure somebody at Fermilab is going to plug the damn thing in, turn it on and my watch is going to stop running, everybody’s hearing aides are going to sail across the room,” Otis said with a laugh. “I have no idea. Turn it on and the Martians will hone in on it.”

Fermilab officials, however, plan to use the magnet in a physics experiment called Muon g-2 that will study subatomic particles at their lab in Batavia, outside Chicago. The experiment will study the properties of muons, subatomic particles that live only 2.2 millionths of a second.

The results of the experiment could create new discoveries in the realm of particle physics, said Chris Polly, manager of the Muon g-2 project at Fermilab.

The hulking magnet is a hand-me-down from New York, where it was built in the 1990s with aluminum and steel by scientists at the Brookhaven National Lab on eastern Long Island. It has superconducting coils inside and, at the time it was built, was the largest electromagnet in the world.

Brookhaven scientists no longer had a need for the electromagnet, and shipping it out to the Midwest for about $3 million was cheaper than the alternative. Constructing an entirely new electromagnet could have cost as much as $30 million, Polly estimated.