Excretory organs of earthworm are nephridia/nephrons.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks whether the excretory organs of earthworms are nephridia or nephrons.

2. **Identifying the Organ**: The excretory organ of earthworms is known as nephridia.

3. **Understanding Earthworm Structure**: Earthworms exhibit metameric segmentation, which means their body is divided into segments called metameres. Each segment is separated by septa.

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