Contractors working in Mantoloking emptied a net meant to catch rocks and debris from the ocean. But along with little pieces of nature, they also found a few pieces of history.

Thanks to four strong storms, seven pieces of munitions from World War I washed ashore.

Contractors found the grenades, which were shot by rifle, while completing a beach replenishment project on coasts affected by Sandy, Mantoloking Councilman Lance White said, and brought them to Joint Base McGuire-Dix-Lakehurst.

"This is the first time they were found here, but [contractors] know to check for them all the time because there are several wrecks in the water," he said.

The century-old munitions were dumped in the ocean after World War I, a practice that was widely accepted until about 1970, said Master Sgt. Bradley Kline, an explosives disposal expert at the base.

"Every so often, they turn up on the shore. It's not uncommon. It's more prevalent after heavy storms," he noted.

Thousands of pieces of munitions have been found in New Jersey, including nearly 2,000 pieces of munition found during a replenishment project in Long Beach Island in 2007.

In 2013, a partially buried German mine was found in Bay Head, exposed after Superstorm Sandy.

Because the munitions are so common, there's not much of a need to keep them, Kline said. Typically, they are detonated as a safety hazard.

"We always err on the side of caution. It needs to be destroyed," he said.

In the wake of a storm-filled month, Kline urges beachgoers and curious history lovers to stay away from anything that looks like it could be something dangerous.

"If you don't know what it is, you probably shouldn't touch it. That's what we do when we find stuff," Kline said.

Sophie Nieto-Munoz may be reached at snietomunoz@njadvancemedia.com. Follow her at @snietomunoz. Find NJ.com on Facebook.

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