First, NASA's Dawn probe spotted curiously sparkly bright spots on the surface of Ceres, the dwarf planet that lies in the asteroid belt between Mars and Jupiter.
Beats us, the scientists said.
Now, cameras on the tractor-trailer-size spacecraft have captured a baffling structure rising 3 miles above the planet's cratered surface.
Conveniently, the thing looks an awful lot like a pyramid.
"Intriguing," the NASA scientists said.
To be fair, the agency offered no suggestion that the towering structure is an offering to some long-lost space emperor or home to our new alien overlords.
And, to be even more fair, it's probably just a really tall mountain in a solar system filled with wondrous and strange natural phenomena.
But the Dawn mission has done nothing but stoke imaginations since the discovery of mysterious bright spots on the surface of the dwarf planet in February and the beginning of the probe's orbit in March.
Folks have claimed to have spotted giant alien motherships hovering over the planet, bat-winged spaceships parked on its surface and even evidence of alien cities.
But the mystery only deepened with the most recent batch of images showing even more bright spots alongside the largest one, which NASA said looks to stretch some 6 miles.
Many, of course, insist that the spots look for all the world like brightly lit cities twinkling on the shadowed surface of the distant dwarf planet.
I knew it! There's gambling going on on Ceres! #aliens pic.twitter.com/QP6PB6JFho
— Chris Reher (@Chris_Reher) June 13, 2015
Of course, NASA hasn't traveled down that road. Scientists, they say, still don't know what the spots are. Maybe ice. Maybe salt.
"But scientists are considering other options, too," NASA said coyly.