'Martian dog' and dozens of other mysterious blobs found hiding under Mars' north pole in new 'gravity map'

Dozens of mysteriously dense blobs — including one surprisingly pooch-shaped structure — are lurking beneath an ancient seabed surrounding Mars' north pole, a new "gravity map" of the Red Planet reveals. The first-of-its-kind atlas also confirms a recent finding about Mars' tallest mountain that could help reveal secrets about the planet's volcanic past and present.

In a new study, researchers created the first true global density map of Mars by combining data about the planet's crust from NASA's InSight lander with records of fluctuations in the orbits of satellites, such as NASA's Mars Reconnaissance Orbiter and the European Space Agency's Mars Express, as they were pulled out of place by hidden gravitational anomalies.

The standout features in the new map were 20 underground blobs in the Borealis Basin in Mars' northern hemisphere, which was an ancient seabed more than 3 billion years ago. These blobs come in a range of shapes and sizes, including one that "resembles the shape of a dog," and have densities between 300 and 400 kilograms per cubic meter higher than the surrounding ground, the researchers wrote in a statement.

However, it is currently unclear what these blobs are, why they are so dense or how they were created.

"These dense structures could be volcanic in origin or could be compacted material due to ancient [meteor] impacts," study lead author Bart Root, a planetary scientist at Delft University of Technology in the Netherlands, said in the statement. And "there seems to be no trace of them at the surface," he added.

The team presented their findings at the Europlanet Science Congress, which was held in Berlin Sept. 8-13.

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