Worms are passive creatures found throughout the Blockhead's world. They were introduced in the v1.2 update, and although they are creatures, worms act as acquired items. Worms are used both as an edible resource food item as well as an item used in the crafting process.
Worms are depicted as a squiggle of reddish brown.
Worms are found by digging dirt (with or without grass) or compost. They are produced randomly and not infrequently at an estimated chance of about 5% per spade stroke, although a spade is not required. In compost, there is a higher chance a worm will be found.
There is no way to ensure a worm will spawn. Only the persistent harvesting of dirt blocks will eventually produce them. Using a spade does not seem to yield more worms, although it saves time.