The microscopic grains of the past are obtained as fossils. Mention the characteristic of the pollen grains that makes it happen.

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the characteristics of pollen grains that allow them to be preserved as fossils.

2. **Identifying the Key Characteristic**: Pollen grains are known for their ability to survive for millions of years, which is crucial for fossilization.

3. **Structure of Pollen Grains**: Pollen grains have a unique structure that includes two layers:
- **Intine**: The inner layer of the pollen grain.
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