Name a fresh water coelenterate.

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the name of a freshwater coelenterate. Coelenterates belong to the phylum Cnidaria.

2. **Identifying the Phylum**: The phylum Cnidaria includes various aquatic animals, which are primarily marine but also includes some freshwater species.

3. **Freshwater Coelenterates**: Among the coelenterates, most are marine, but there are a few genera that are found in freshwater environments.

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