A mysterious black substance washing on the shores of Ortley Beach was identified as peat, according to the Army Corps of Engineers.

The Corps is in the middle of a 14-mile beach replenishment and dune construction project along the Barnegat Peninsula.

Beachgoers told News 12 New Jersey that a black, brittle substance began washing up on the beach this week and that they were not sure what it was.

The Army Corps says a geotechnical investigation took place and discovered that the dredge has hit a peat layer offshore.

“Peat is a naturally occurring material and is typically a combination of ancient soil and vegetative materials,” a spokesperson for the Corps said in a statement.

The statement said that the Corps will work with the New Jersey Department of Environmental Protection to make sure the materials that wash up during the dredging are kept “at the absolute minimum.” The Corps says that the substance “present[s] no danger to the environment or public.”