Excerpt from Gentoo's wikipedia article:A Gentoo Penguin is the fastest-swimming of the penguin family. The name evokes an image of speed, while retaining the penguin as a generic mascot for Linux.
The official Gentoo logo is a stylized 'g' resembling a silver magatama.[61] Unofficial mascots include Larry The Cow[3] and Znurt the Flying Saucer.[62]
https://en.wikipedia.org/wiki/Gentoo_Linux#Logo_and_mascots
