Why is Antedon called living fossil.

Explanation

### Step-by-Step Solution:

1. **Definition of Living Fossil**:
- A living fossil is an organism that has remained relatively unchanged over long geological periods and retains primitive features similar to its ancestors.

2. **Introduction to Antedon**:
- Antedon, commonly known as the Feather Star, belongs to the phylum Echinodermata.

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