The Spanish for “leather,” cuero, comes from the Latin corium meaning, “leather or hide.” From that root, we get a few English words, including… cork. A cork is made from the the hide of a tree, after all!
From the same root we also get cortex (the tree that runs up your spine!), scrotum (feels like a skin, doesn’t it?)
We can see the c‑r root clearly in all these words!