LOS ANGELES — The more Curiosity gets to know Mars, the more it seems like a big red Earth. Curiosity recently examined what appeared to be an ancient riverbed and conglomerate rocks similar to those at home. Now comes “Jake Matijevic” — a pyramid-shaped chunk of rock that’s proved to be a surprise, even to NASA.

The space agency says that Jake, named for a legendary NASA engineer, is unique — unlike any rocks examined before on Mars. And that’s saying something. Previous rovers have examined hundreds of Martian rocks.

When Curiosity team members picked Jake, they were just hoping for a “simple and uniform” rock that would help them compare results from two chemistry instruments.