When Glenn Maxham of Duluth showed up at the Minnesota Sea Grant office earlier this month, he didn't know he was carrying "whale burps."

That's what Sea Grant officials eventually called the two fibrous balls of natural debris and shards of plastic that Maxham's son, Scott Maxham, had found in the shallows of Lake Superior along Duluth's Lakewalk over the Thanksgiving weekend.

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"He said there were a whole bunch of them along the shore," Maxham said. "I was curious to know what the balls were made of."

The balls that Maxham delivered to Sea Grant were about 2½ inches in diameter. They appear to consist of grasses, twigs, a bird feather and degraded polymer mesh, said Sharon Moen, science writer and interim communications coordinator at Sea Grant.

The balls apparently were made through wind or current action on the lake. The plastic in them is not fishing line, Moen said.

"There are strands of black plastic. It looks like it could be part of a silt fence, the kind used in construction," Moen said.

It turns out that the so-called "whale burps" or "surf balls" have been found along the Oregon coastline, too. Scientists have found surf balls made of fine vegetative strands on Egyptian beaches and surf balls twice the size of a large orange on Australian shores, Moen said.

The term "whale burps" was used by the Oregon Sea Grant office, but nobody knows where the phrase originated, Moen said.

Moen solved the mystery of the whale burps simply by Googling "beach debris balls" and finding the Oregon Sea Grant website, she said.

"Beach balls are prickly balls that look like balls of straw and are found on beaches. They are sometimes sold in gift shops as 'whale burps,' 'whale barf balls,' or 'whale fur balls,' writes Vicki Osis, a marine education specialist with the Oregon Sea Grant office at Oregon State University.

Apparently, no similar beach debris balls have been found anywhere else on the Great Lakes.

"We don't have any information like that yet," Moen said. "We hope that our talking about it will generate some discussion."

The magazine Science Monthly reported in 1948 finding balls of common ditch grass up to a foot in diameter on Little Borax Lake in California, Moen said.

Sea Grant would welcome more samples of the surf balls, Moen said.

"By all means, go out there and look for treasures on the beaches," she said, "and while you do it, carry a trash bag and pick up any plastics. They last a lot longer in the environment than paper and metals."

According to Sarah Erickson of the Great Lakes Aquarium, about one-third of all items collected in the 2010 Beach Sweep in St. Louis and Lake counties on Lake Superior were plastics.