Oumuamua

Oumuamua is an interstellar object that was discovered in 2017. It was the first interstellar object to visit the solar system. It is 45 m long and possibly composed of frozen nitrogen. According to recent study, the object is the remnant of Pluto sized celestial object and is shaped like a cookie. According to the authors, the object was created by an impact some 500 million year ago. Another interstellar object that visited the solar system (in 2019) is Borisov.