Sandworms are purchased from Tynan's Fishing Supplies in Great Kourend's Piscarilius House. They are used as bait with a fishing rod to catch anglerfish.
When catching sandworms on the shores of Piscarillius with a spade and buckets, the player may receive Hunter experience. It is a decent method for low-level moneymaking, netting upwards of 100-150k per hour.