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As scientists search for worlds that may be habitable for life, they’ve discovered a type that is common in the universe — but doesn’t exist in our own solar system.

These enigmatic planets are called sub-Neptunes, which are larger than Earth but smaller than Neptune.

An April study catapulted one such world, named K2-18b, into the spotlight. Astronomers at the University of Cambridge claimed they detected molecules in the planet’s atmosphere that might be biosignatures — markers of biological activity that could hint at past or present life.

Now, other groups of astronomers have looked at the same data and disagree with the findin