Gamets are species found in the Metroid series of games, including and currently limited to Metroid, Metroid: Zero Mission and Super Metroid. They're relatively large creatures who posses the ability to fly.
They seem to be protected by their shell that covers their heads, though ultimately they can be killed by Samus Aran, the protagonist of the series. They, along with hundreds of other species that were native to Zebes, became extinct once their planet was destroyed. While it is possible that some live elsewhere, it isn't very likely.
In the games two types have been spotted, blue and red, with the former version being stronger. Once they pop out of their holes which are mounted on walls, they fly forward without turning around until they find another hole (usually across from them).