The carcass of a basking shark at least 24 feet long that was first seen stuck to the bow of a container ship in Boston Harbor more than two weeks ago has resurfaced.

A New England Aquarium spokesman says officials at first weren't sure what kind of marine creature it was Tuesday.

Tony Lacasse says aquarium biologists who went to scene determined it was a shark based on its cartilaginous fins.

It's unclear if the creature was killed by the ship strike or if it was already dead. It probably weighed 3 to 5 tons when alive.

Basking sharks are the world's second-largest sharks. They feed on plankton and are generally harmless to humans. Because of their prominent dorsal fin, they are often confused with great whites.