"Tar balls" refers to clumps or blobs of thick, sticky tar that are often found on beaches or in the ocean. They are formed when oil from sources like oil spills or natural seeps combines with sand or sediment in the water. Full definition
But the microbes will eventually devour all of BP's Gulf of Mexico oil spill — no matter where it ends up — except the heaviest, nastiest stuff: asphaltenes and other big - chain hydrocarbons that go on to form the millions of tar balls dotting the world's oceans. (scientificamerican.com)
Substituting the pipeline for more deep water platforms would lower the risk of more tar balls on Southern beaches. (treehugger.com)
[2] The liquid petroleum produces a slick that is many kilometres long and when degraded by evaporation and weathering, produces tar balls which wash up on the beaches for miles around. (en.wikipedia.org)