The sewer monster is made up of thousands of tiny organisms called bryozoans, or moss animacules, said N.C. State University biologist Thomas Kwak. Invertebrates, they bunch together in colonies and feed with tiny tentacles.
"They can get as big as the size of a watermelon," he said.
They've been known to clog pipes, but Raleigh officials aren't worried, even though bryozoans can move up to 10 centimeters a day. "I don't know if we've seen anything move on its own inside a sanitary sewer line," Public Utilities Director Dale Crisp said.