The Living Pickaxe is a tool added by Roots. Unlike regular pickaxes, it will heal over time; each tick, it will have a 1/80 chance to restore one durability (so there is a 22.25% chance of at least one durability point being restored every second).
The Living Pickaxe is created in a Ritual. It requires a Wooden Pickaxe, a Verdant Sprig and a Gold Ingot to be placed on the Casting Altar and two Oak Barks to be burned in the Incense Brazier.
— Runic Tablet
Your rituals are capable of channeling life energy into previously dead objects. Using this, you can grow newer, stronger forms for your wooden tools. Adding a little gold for reinforcement, as well as a verdant sprig to grow upon, will grant you tools of similar strength to iron that repair slowly over time.