The phrase “Never Forget” has become a rallying cry to honor the thousands of lives lost nearly 20 years ago at the World Trade Center.

The 9/11 Memorial and Museum features the names of the men and women who perished. It also honors the first responders who worked tirelessly in the days, weeks and months after the tragedy. But they weren't alone in their efforts. Canines were also at ground zero, an essential part of the search and rescue efforts.

Senior Curator Amy Weinstein helped make a new exhibit at the museum to honor the dogs' heroic efforts. It's called “K-9 Courage” and includes pictures from 2001, as well as portraits taken years later of some of the service dogs, their handlers and veterinarians.

“The dogs resonated so much with people in 2001 at a time it felt they were the only hope of finding anyone alive,” Weinstein told NY1.

Among the artifacts, a brush that belonged to a canine named Sirius. He and his handler were based at the towers, but the dog did not survive.

“It’s was a way that Sirius can be remembered. At lot of people don’t realize that a dog was killed on that day,” said retired Port Authority Police Lieutenant David Lim.

The exhibit includes photos and artifacts of about two dozen dogs, but curators say many other canines helped out after the 9/11 attacks.

Visitors got to also see a presentation by officers who work with dogs trained to detect explosives.

For Transportation Security Specialist Lawrence Sharp, this is a full circle moment. He was so inspired by seeing the images of the services dogs at ground zero, it became his calling.

“9/11 directly affected me and made me want to join the TSA in the first place,” said Sharp. “Once I found the canine program existed within the TSA, that was my one goal to qualify to be a part of that program.”

Along with their handlers, the canines risk their lives to keep humans safe, living up to their reputation as man's best friend.