| Clue | Source | Date |
|---|---|---|
| Like some rocks, since covered by the sea | ||
| When in sea, it's rocky | The Telegraph Toughie | 20 Oct 2016 |
| CIA blast possibly connected with volcanic rock | ||
| Like rock when surrounded by sea | The Telegraph Toughie | 17 May 2016 |
| Rocky, as in sea | ||
| Like dark igneous rock | ||
| Like rock found at midocean ridges | ||
| Like much Hawaiian lava | ||
| Like much Hawaiian lava | ||
| Like the Rosetta Stone | ||
| Like some lava | ||
| Like block lava | ||
| Like block lava | ||
| Of a dark, volcanic rock | ||
| Type of volcanic rock |