US National Park Service: What are these weird creatures that washed up on the beach?

The US National Park Service found two of these weird creatures washed up on North Carolina's Cape Lookout National Seashore and is wondering what the hell they are.

"Our turtle patrol found them on the ocean side beach recently adjacent to a log covered in goose-neck barnacles (no idea if they are connected to the log or if its just a coincidence), they wrote on Facebook. "So far, we're stumped as to what they might be. They were about 6 inches long and no longer alive.

"One guess was they might be a form of sea cucumber (or sea slug?), but they couldn't be matched to any images that were posted online."

Commenters on the post suggest they could be polychaetes (commonly called bristle worms), but I think they are more likely extraterrestrial larvae and we should be very thankful that they died before reaching maturity.