What is notochord? Give its function.

Explanation

### Step-by-Step Solution:

1. **Definition of Notochord**:
- The notochord is a rod-like structure that is located on the dorsal side (the back side) of an organism. It is a flexible, supportive structure that runs along the length of the body.

2. **Location**:
- The notochord is situated between the gut (digestive system) and the nervous system. This positioning is crucial for the development of the organism's body plan.

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