The phrase "turned bone" refers to a process where bone material is transformed, typically becoming harder and more brittle. Some synonyms for this phrase might include "calcified," "ossified," or "solidified." These terms all convey the idea of bone material undergoing a change, becoming denser and more solid over time. Other potential synonyms for "turned bone" might include "hardened," "petrified," or "fossilized." Regardless of the specific word chosen, each of these synonyms helps to capture the sense of transformation and change that takes place when bone material undergoes this process, resulting in stronger, more durable material over time.