"'Oumuamua is in a different category of object. It's much harder to find, but there are a lot more of them."

The first interstellar object to visit the solar system may have been a fragment of an icy exoplanet, research suggests.

Everything about this object is consistent with it being a slab of nitrogen ice like you see on the surface of Pluto.

Instead of being a mix of water ice, rock and carbon-rich material left over from the formation of the solar system, 'Oumuamua appears to be almost pure nitrogen ice. And rather than being a compact ball, the visitor is more elongated than any known body in the solar system and starkly different from the interstellar Comets 2I/Borisov and 3I/ATLAS, the only other known interstellar visitors.