Entity: Cavernstalker Kobold

Source Player Core 2 pg. 21 ^1.1

You hatched in a warren with narrow tunnels that was also home to a being of primal earth energy, which has made you limber and flexible. When Climbing rock walls, stalactites, and other natural stone features, you move at half your Speed on a success and at full Speed on a critical success (and you move at full Speed on a success if you have Quick Climb). This doesn't affect you if you're using a climb Speed. If you roll a success on an Acrobatics check to Squeeze, you get a critical success instead.