However, its flattened, elongated shape, combined with the way it accelerated on its way through the solar system set it apart from conventional asteroids and comets.
While it's not explicitly clear that Oumuamua was sent by aliens, researchers used meticulous mathematical analysis to make the case that the object was a "lightsail of artificial origin" due to the way it sped up as it passed by the sun.
"But it's important to distinguish that the researchers who wrote the new paper have expertise in solar sails, so they're suggesting that "Oumuamua could be like a solar sail, said Coryn Bailer-Jones of the Max Planck Institute for Astronomy".
Oumuamua, which translates as "distant messenger from the past" in Hawaiian, can reach speeds of up to 196,000mph.
Multiple telescopes focused on the object for three nights to determine what it was before it moved out of sight. After being described as an asteroid, a team of the European Space Agency estimated in June 2018 that it was more likely a comet - with ice that turns into gas near the Sun.
But until science tells us that it definitely isn't, we'd like to believe that it is.
To explain its movement, the report's authors, Abraham Loeb, a professor and chair of astronomy, and Shmuel Bialy, a postdoctoral fellow, argue that Oumuamua's non-gravitational acceleration may be explained by solar radiation pressure.
The cigar-shaped rock is now speeding through the galaxy and is the first known interstellar object to enter our solar system.
"Not 'where is the lack of evidence so that I can fit in any hypothesis that I like?"
So far, there is no obvious origin for 'Oumuamua.
If Oumuamua is evidence of an alien civilization seeking out life beyond its home solar system, we may never know.
It's also entirely possible - perhaps more possible - that the object isn't part of a far-flung alien race's attempts to investigate the (other) occupants of the Milky Way. "You have to understand that for scientists, the craziest idea is always publishable, as long as there is a tiny chance that it is not wrong", she wrote on Twitter. "But until every other possibility has been exhausted a dozen times over, even the authors probably don't believe it".
The truth may be hard to establish, as Oumuamua has left the solar system and is no longer visible even with telescopes.
"The likelihood of Galactic panspermia is strongly dependent upon the survival lifetime of the putative organisms as well as the velocity of the transporter", Manasvi Lingam and Loeb from this current study said in another paper published previously in the Astrophysical Journal.