When it comes to contact and attention, reptiles have a reputation for being pretty cold. It’s hard to imagine a toddler snuggling with an iguana, or a python slithering over to greet its owner at the door. But we shouldn’t be so quick to judge. Some reptiles, including tortoises, do enjoy physical contact.

The tortoise’s shell is a living, growing exoskeleton composed of keratin—the same stuff that makes up your fingernails. But unlike your nails, the shell is packed with nerve endings that make it sensitive to touch.

In this video from the Smithsonian, herpetologist Matt Evans makes his daily visit to the National Zoo's tortoise enclosure. The attention and chin scratches are actually part of the tortoises’ daily enrichment—a fact that seems to suit these animals just fine. 

Header image via Smithsonian Channel, YouTube