A new species of frog discovered in Ecuador is the first vertebrate known to change its skin texture from smooth to spiny, researchers say.

The mutable species of rain frog possesses an ability previously observed only with invertebrates such as cuttlefish and octopuses. Around moss — plentiful in its native Ecuadorean forest — the frog sprouts tiny tubercles, presumably as camouflage. Away from the moss, the tubercles rapidly recede and the frog’s skin turns smooth.

Researchers discovered the tiny frog (about the size of a marble) in 2006, but it was three years before they observed its shifting abilities.

“We took a specimen back to the house in a cup to photograph it, and when we looked in the morning, we thought we had grabbed the wrong frog,” said Katherine Krynak, a biologist at Case Western Reserve University and an author of the study. “We put the frog back in the cup with some moss, and soon, it had the spines again.”