Aliens may already live on Earth, Harvard researchers say

Mainstream-ish news:
A new study by Harvard social science researchers suggests that aliens may have been living on Earth for a while. The research paper—which is yet to be peer-reviewed—suggests that life forms from other worlds could be living underground on Earth or within the moon, and that UFOs and other unidentified anomalous phenomena (UAP) may in fact be evidence for them getting around.

Aliens May Already Live on Earth, Harvard Researchers Say – Newsweek