Turtles may chew on driftwood to wear down their beak, which is similar to fingernails and grows slowly over time. Driftwood provides a natural way for turtles to keep their beak in check. However, it is important to ensure that the driftwood is safe and does not contain toxins or break down too quickly. The addition of cuttlebone to the tank can also provide a suitable alternative for turtles to chew on and help wear down their beak.