Tar balls have been washing up on the beaches of some Monmouth County shore towns. They range from golf ball size to the size of a pea.

The Coast Guard is now trying to determine where the contaminants are coming from.

The tar balls have been found on beaches from Sea Bright to the south in Allenhurst, a nine-mile stretch of shoreline.

The nonprofit Clean Ocean Action started getting calls from surfers and walkers about it and found quite a lot had washed up in the surf.

Kari Martin is with Clean Ocean Action. Members of her organization saw evidence of the tar balls at Seven Presidents Beach in Long Branch.

“It’s a petroleum-based product. I don’t know the origin or what type of oil it could be, but it’s a petroleum-based product loaded with chemicals,” Martin says.

As cleanup efforts take place, the Coast Guard will be testing the tar balls in an attempt to determine the origin of the substance.