Mysterious rock-like pieces discovered along Keyport’s shore have been confirmed as toxic lead.

From a distance, the hard, oddly-shaped chunks don't look different from the rocks that make up Keyport’s shore. But, they’re actually “slag” - a byproduct of manufacturing metals - and they’ve tested positive for lead.

“It’s clearly dumped there because it's just concentrated in certain areas,” NY/NJ Baykeeper Greg Remaud said. “People need to know as soon as possible.”

Remaud said he’s seen slag containing lead in Laurence Harbor before.

It’s not yet clear where the lead came from, but Remaud says there are nearby Superfund and industrial sites that he was originally investigating when he found the slag.

“People wade in these waters, they fish in these waters,” Remaud said. “If they eat crabs and fish that have lead in them, it gets into their bodies.”

Remaud says lead exposure is associated with developmental disorders in children.

The DEP and EPA are investigating who’s responsible. They’ll have to clean the water and then pay up.

“It's logical to believe that there's small particles that are in these waters and in this sediment,” Remaud said.

But unless the town or a federal agency marks the land, there’s no visual indication that there’s lead on the shore.

“You can just put some tape up, something saying ‘temporarily closed,’” Remaud said. “It's a small area. People can just go there, their dogs can jump in the water as they often do. They may be exposed.”