We know of three interstellar objects (ISO) that have visited our inner Solar System. Oumuamua was the first one, and it came and went in 2017.

2l/Borisov, an interstellar comet, was next, appearing in 2019. And right now, the interstellar comet 3I/Atlas is enjoying a visit to the Sun-warmed inner Solar System.

A massive number of ISOs must have passed through our Solar System during its long, 4.6 billion-year history. It’s possible that some of them slammed into Earth.