| Clue | Source | Date |
|---|---|---|
| Turned to bone | The Times Concise | 10 Sep 2025 |
| Became bone-like through age | ||
| Converted to or hardened like bone (8) | ||
| Turned to bone | The Times Concise | 11 Jun 2022 |
| Fossilised, petrified | ||
| Fossilised, petrified | ||
| Fossilised, petrified | ||
| Turned to bone | Eugene Sheffer | 31 Oct 2020 |
| Turned to bone with age | ||
| Turned into bone | ||
| Turned to bone | ||
| Changed into bone | ||
| Hardened into bone | ||
| Ultraconservative | ||
| Hardened | ||
| Fixed rigidly in a custom. |