The dead remains of diatoms are known as :-

Options

A. Coenobium
B. Sporangia
C. Kieselgurh
D. Sporocarp

Answer

### Step-by-Step Solution:

1. **Understanding Diatoms**: Diatoms are a type of microalgae characterized by their unique silica cell walls. They are found in aquatic environments and play a crucial role in the ecosystem.

2. **Identifying the Dead Remains**: The question asks for the term that refers to the dead remains of diatoms. Diatoms, when they die, leave behind their silica shells.

3. **Exploring the Options**:
- **Caenobium**: This term refers to a loose mass of colonial organisms that live together in water bodies. It does not pertain to the dead remains of diatoms.
- **Sporangia**: These are structures that contain spores and are involved in the reproductive process of certain organisms, like slime molds. This is also not related to diatoms.
- **Kaiselgarh**: This term specifically refers to the dead remains of diatoms, which accumulate as diatomaceous earth due to the non-degradable nature of their silica shells.

4. **Conclusion**: Based on the analysis of the options, the correct answer to the question is **Kaiselgarh**.

### Final Answer:
The dead remains of diatoms are known as **Kaiselgarh**.

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