Which one is the most primitive molluse ?

Options

A. Chiton
B. dentalium
C. Neopilina
D. Patalla

Answer

To determine the most primitive mollusk, we can follow these steps:

### Step 1: Understand the Phylum Mollusca
- The Phylum Mollusca is known for its vast diversity and is considered the largest marine phylum. It includes a wide variety of organisms, ranging from simple to complex.

### Step 2: Identify Primitive Characteristics
- Primitive organisms typically exhibit simpler structures and fewer specialized features. In the case of mollusks, we are looking for those that retain characteristics similar to ancestral forms.

### Step 3: Research Neopilina
- In the 1950s, a mollusk named Neopilina was discovered. This organism is considered very primitive due to its simple structure and the presence of characteristics that are also found in Annelids (segmented worms).

### Step 4: Classification of Neopilina
- Neopilina belongs to the group Monoplacophora, which is characterized by having a single, cap-like shell. This simplicity is a key factor in its classification as a primitive mollusk.

### Step 5: Compare with Other Mollusks
- Other options like Dentalium, Chiton, and Patella are more complex in structure. Dentalium has a tooth-like structure, Chiton has a chitinous exoskeleton, and Patella has a hard shell resembling a knee cap.

### Conclusion
- Based on the characteristics and classification, Neopilina is recognized as the most primitive mollusk.

### Final Answer
- The most primitive mollusk is **Neopilina**.

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