St. Petersburg Beach, FL -- There were some frightening moments Thursday morning on St. Petersburg Beach when a treasure hunter sweeping the area with a metal detector got far more than he bargained for: hand grenade.

It happened at about 10 a.m. as the man was sweeping the sandy bottom in waist-high water behind the Sirata Beach Resort

It turns out it was an old military grenade, and had probably been there for quite some time. Inert, say sheriff's deputies.

But the men who found it had no way of knowing that when they pulled it out of the water.

"This definitely makes for the most interesting day of metal detecting, yeah," said Cliff Vogan, 61.

Vogan has been treasure hunting along Bay area beaches for about five years now, and has found some odd things before including a bicycle, even a fire extinguisher, he says.

Most weekends you’ll find Dave Rees out in the countryside with his metal detector, sweeping the ground and waiting for a tell-tale beep.

The moment there’s a promising tone he’s down on his hands and knees, eagerly scraping away at the surface of the ground with a trowel.

The 66-year-old recently unearthed a 2,000-year-old Roman coin in a field in Wiltshire, to add to his small collection of ancient finds.

Published: Sunday, September 28, 2014 at 05:08 PM.

Jerry Barbee can’t begin to count the number of rings, Civil War relics and coins he’s collected through his four decades of metal detecting, but he can certainly remember the first silver coin he found.

His daughter Libby lost her half dollar in the yard on her way to the bus.  With his metal detector in hand, he was able to find the coin and return it to his daughter.

“I’ve always been interested in discovery and the anticipation of discovery,” he said. “I love to discover things, especially older things.”