Comprised of silicate rock, the asteroid rolls through its eccentric orbit like a tumbling potato.

CNN: NEAR and Eros

Curiosity was landing on Mars in an uneasy season, when the planet was swinging closer to the sun on its eccentric orbit, stirring up an already volatile climate.

NEWYORKER: The Martian Chroniclers

The second piece of evidence pointing to is the eccentric orbit of an existing planet around the star, which is in an orbit not normally expected in this type of system.

FORBES: Astronomers Discover A Star That May Have Destroyed Its Own Planet

In their paper, the co-authors argue that gravitational tidal heating caused by the gravitational friction of an earth-like exo-moon on an eccentric orbit around a Jupiter-like planet lying at a Jupiter-like distance from its parent star, could, in fact, create habitable conditions.

FORBES: Earth-Like Exo-Moons Can Lurk Well Beyond Planetary Habitable Zones, Say Astronomers

One way they could have got there is if multiple planets have interacted in a gravitational "billiards game", in which one planet might have been flung in towards the parent star (sometimes to be swallowed whole), while another might have been thrown into an eccentric orbit, or perhaps even ejected from the system altogether.

BBC: Star 'eats' a planet