Remember Oumuamua? Of course you do!
It was a hunk of rock from another star system, the first we've ever seen. And it was weird, long and skinny, unlike anything in our solar system.
Well? It just got weirder.
Some tall foreheads from Harvard think it might be an
Read all about it here.
They think it may have used, or is still using, light-sails. Usually found in Sci-Fi stories, it is a very real and valid form of propulsion. But slow, and kind of useless when too far away from a star.