For Dan O'Meara, it was a routine sweep. An engine company from the Fresno Fire Department had just put out a neighborhood fire, and O’Meara’s team was assigned to make sure everything was extinguished. It seemed to be—till they happened to peek beneath a wooden deck in a backyard.

“My captain said, Looks like there’s a bunch of stuff under there, let’s pull it all out,” says O’Meara, a 21-year veteran of the department and now a captain there himself. “We started clearing everything out, and then we saw it—a glowing ember, sitting right there, smoldering by itself. That was lucky. If we hadn’t found it, it would have burned the house right to the ground.”

Embers may remind you of a