Aulocantha is

Options

A. Radiolarian
B. Foraminifer
C. Amoebid
D. Heliozoan.

Answer

**Step-by-Step Solution:**

1. **Identify the Organism**: The question asks about Aulocantha. We need to determine which category it belongs to among the given options: Radiolarian, Amino, Amoebite, or Heliozone.

2. **Understanding Aulocantha**: Aulocantha is described as a single-celled aquatic organism. It has a spherical, amoeba-like body and a spiny skeleton made of silica.

3. **Relate to Radiolarians**: Radiolarians are known for having skeletons made of silica, similar to Aulocantha. They possess a structure composed of hydrated amorphous silica and spines, which aligns with the characteristics of Aulocantha.

4. **Evaluate Other Options**:
- **Aminifers**: These are marine protists with a different structure (calcareous or organic tests) and do not share the silica skeleton characteristic with Aulocantha.
- **Amoebite**: This term refers to a type of cell or organism that can change shape but does not represent a specific taxonomic group. Aulocantha is not classified as an amoeba.
- **Heliozone**: These are also microbial eukaryotic protists but have different structural features (like stiff arms) and do not match the characteristics of Aulocantha.

5. **Conclusion**: Based on the analysis, Aulocantha fits the definition of a Radiolarian due to its silica skeleton and aquatic nature. Therefore, the correct answer is that Aulocantha is a Radiolarian.

**Final Answer**: Aulocantha is a Radiolarian.

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