The elephant tusk shell is

Options

A. Dentalium
B. Limax
C. Cypraea
D. Nautilus

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks about the elephant tusk shell and provides four options: Dentalium, Limex, Cypria, and Nautilus.

2. **Understanding the Elephant Tusk Shell**: The elephant tusk shell is specifically known as Dentalium. It is a type of mollusk that belongs to the class Scaphopoda.

3. **Characteristics of Dentalium**: Dentalium shells are elongated and resemble an elephant's tusk. They are open at both ends and are relatively small in size.

4. **Analyzing Other Options**:
- **Limex**: This is a genus of air-breathing land slugs, which do not resemble the elephant tusk shell.
- **Cypria**: This refers to a type of marine gastropod mollusk, commonly known as large sea snails, which also do not match the description of the elephant tusk shell.
- **Nautilus**: This is a pelagic marine mollusk belonging to the cephalopod family, which is distinctly different from the tusk shell.

5. **Conclusion**: Based on the characteristics and classifications discussed, the correct answer to the question is **Dentalium**.

**Final Answer**: The elephant tusk shell is **Dentalium**.

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