Question: Primary succession is the type of succession that occurs on bare rock with no soil. What organism can help turn rock into soil?
1. The problem asks which organism helps turn bare rock into soil during primary succession.
2. Primary succession occurs in lifeless areas where there is no soil, such as bare rock.
3. Organisms that can colonize bare rock and contribute to soil formation are called pioneer species.
4. Lichens are pioneer species that can grow on bare rock.
5. Lichens secrete acids that chemically weather the rock, breaking it down into smaller particles.
6. As lichens die and decompose, they add organic material, gradually forming soil.
7. Deer do not contribute to soil formation on bare rock; they are animals that depend on existing vegetation.
8. Therefore, the correct answer is **Lichen**.
Final answer: Lichen