In which group of organisms the cell walls from two thin overlapping shells which fit together?

Options

A. Dinoflagellates
B. Slime moulds
C. Chrysophytes
D. Euglenoids

Answer

To answer the question regarding which group of organisms has cell walls that form two thin overlapping shells that fit together, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Groups of Organisms**: The question provides four options: Dinoflagellates, Slimos, Chrysophytes, and Euglenaids.

2. **Analyze Each Group**:
- **Dinoflagellates**: These are primarily marine plankton and have a unique cell wall structure, but they do not have the characteristic of overlapping shells.
- **Slimos**: This group is not commonly recognized in standard biological classification, and thus we can disregard it for this question.
- **Chrysophytes**: This group includes organisms like diatoms and golden algae. Diatoms are known for their unique silica-based cell walls.
- **Euglenaids**: These are flagellated protists that have a flexible pellicle instead of a rigid cell wall.

3. **Focus on Chrysophytes**: Within Chrysophytes, diatoms specifically have cell walls made of silica that form two thin overlapping shells, known as frustules. These frustules fit together like a petri dish.

4. **Conclusion**: The group of organisms that has cell walls forming two thin overlapping shells that fit together is **Chrysophytes**, particularly the diatoms.

### Final Answer:
**Chrysophytes** (specifically diatoms) are the group of organisms whose cell walls form two thin overlapping shells that fit together.

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