What is the most prominent feature of the phylum Annelida?
List three familiar forms of Annelida.

Explanation

**Step-by-Step Solution:**

1. **Identify the Prominent Feature of Phylum Annelida:**
- The most prominent feature of the phylum Annelida is the presence of true segmentation in their body. This means that their body is divided into repeated segments, both externally and internally.

2. **Describe Additional Features:**
- Annelids are the first true coelomates, meaning they possess a true coelom (a body cavity lined with mesoderm).
- They have a complex organ system organization, which includes a closed circulatory system.
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