“Tiny, super-intelligent” aliens may have already visited Earth — but humans simply didn’t notice them, a NASA scientist claims in a new research paper.

Silvano P. Colombano, of NASA’s Intelligent Systems Division, argued in a recent research paper that extraterrestrials may look different than what we expect and may be able to travel huge distances — and so we may have never realized that they’d paid us a visit.

“I simply want to point out the fact that the intelligence we might find and that might choose to find us (if it hasn’t already) might not be at all be produced by carbon based organisms like us,” Colombano wrote in “New Assumptions to Guide SETI Research.”

If the aliens aren’t carbon-based life forms, that would alter what we look for when we think about interstellar visitors, argued Colombano, of NASA’s Ames Research Center in California.

“Our typical life-spans would no longer be a limitation … and the size of the ‘explorer’ might be that of an extremely tiny super-intelligent entity,” Colombano wrote.

The computer scientist also suggests ETs may have figured out technology that humans just can’t understand.

This would change our assumptions about interstellar travel, namely, that it’s impossible.

“If we adopt a new set of assumptions about what forms of higher intelligence and technology we might find, some of those phenomena might fit specific hypotheses, and we could start some serious inquiry,” he suggested.

The space expert encouraged his colleagues to be more open-minded about the possibility of alien visitors and said not all UFO sightings can necessarily be “explained or denied.”

Colombano presented his paper at a workshop called “Decoding Alien Intelligence” organized by NASA’s SETI Institute, which stands for “Search for Extraterrestrial Intelligence,” last March.