Which mollusca is called tusk shell :-

Options

A. Neopilina
B. Pila
C. Dentalium
D. Doris

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which mollusk is referred to as a "tusk shell." This requires knowledge of different types of mollusks and their common names.

2. **Analyzing the Options**:
- **Option 1: Nuculana**: This is incorrect. Nuculana is a genus of bivalve mollusks and serves as a connecting link between annelids and mollusks, but it is not known as a tusk shell.
- **Option 2: Pila**: This option is also incorrect. Pila refers to a genus of freshwater snails that possess an operculum, but they are not called tusk shells.
- **Option 3: Dentalium**: This is the correct answer. Dentalium is a genus of mollusks commonly known as tusk shells due to their elongated, tusk-like shape.
- **Option 4: Doris**: This option is incorrect as well. Doris refers to a genus of marine gastropod mollusks, which are not known as tusk shells.

3. **Conclusion**: After evaluating all the options, the correct answer is **Dentalium**, which is the mollusk referred to as a tusk shell.

**Final Answer**: Dentalium

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