The Corvan gilvos were a stick-like animal indigenous to the rainforests of Corvan II. Gilvos were uniquely suited to live in trees, as they closely resembled a tree branch. Their eating habits were similar to Earth's extinct Draco lizards. Their habitat was threatened by industrial pollutants on Corvan II, and by 2368, there were only fourteen gilvos left in the wild.

That year, the USS Enterprise-D transported two gilvos to the protected planet of Brentalia. Miss Kyle showed them to her class, which included Alexander. Later, Worf had promised his son that he could see them again, but decided not to, because the boy had misbehaved and lied to him.

During their stay in the biolab, the gilvos were momentarily threatened by a fire that broke out, but Commander William T. Riker was able to save the animals, at Alexander's insistence, the Klingon having gone there alone to see them anyway. (TNG: "New Ground")

Another surviving gilvo was a pet of Grand Nagus Quark in 2369. (DS9: "The Nagus")