“Exocomet” is probably a new word to you. We know exoplanets as planets that revolve around stars outside our solar system. Exocomets are comets that revolve around stars outside our solar system. Astronomers assumed that they were out there somewhere, but only recently have we seen evidence of them. And like exoplanets, they are too far away to see, but we have evidence that comes from those far away stars themselves. One exocomet was detected around a star 815 light-years away, and another at 850 light-years away.
Source: Alien Comets: Evidence of Exocomets – Neatorama