Therapy dogs are nice, George "Geo" Caldwell thinks, but there is something fundamentally different about llamas.

"There's something about when you're at the same eye level," he said. "You get this sense that there's this communication and form of energy going between the two of you."

Cadwell is responsible for the newest quirky Cal tradition: the biannual appearance of fluffy, dewy-eyed llamas on campus grounds.

During the class-free week before finals (officially called "De-Stress Week" but long known as "Dead Week" by students), anxious co-eds can stop by the campus' central Memorial Glade to pet and feed the llamas.

There are plenty of other purportedly stress-reducing events around finals season, many of which change from year to year, but the llamas have become an institution. Mention of them can be found in the Daily Californian as far back as 2014. Even now, though, they never fail to raise a few eyebrows.

Cadwell is paid by the UC Berkeley student government for his quadruped friends' seasonal visits, but he's brought them to other events pro-bono, like the yearly suicide prevention walk. They're important, he said, and he wishes the school could have its own in-house llama herd.

The llamas, for their part, are trained and comfortable around people. Students can hug them, feed them alfalfa pellets and carrots, and pose with the expressive animals for the obligatory selfie.

The phenomenon of therapy animals has swelled in popularity in recent years. San Francisco International Airport has a therapy pig, and worried office workers can pay to snuggle adoptable kittens and puppies at the O'Farrell St. Macy's. Therapy-animal proponents believe that even brief contact with animals provides mental health benefits.

Of course, there is room for skepticism. One recent literature review failed to find much conclusive evidence of their effectiveness. But Cadwell can attest to the smiles his llamas bring.

"It just brings happiness to people," he said. "It's a magical thing."