Boring spong is

Options

A. Cliona
B. Chalina
C. Euplectella
D. hyalonema

Answer

To determine which sponge is referred to as the "boring sponge," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Phylum**:
- The question mentions "boring sponges." We know that sponges belong to the phylum Porifera.

2. **Understand Sponge Characteristics**:
- Sponges are generally marine animals that are mostly asymmetric. They have a cellular level of organization and are considered primitive multicellular organisms.

3. **Water Transport System**:
- Sponges have a unique water transport system that involves minute pores called ostia, through which water enters. The water circulates inside a cavity called the spongocoel and exits through an opening called the osculum.

4. **Focus on Boring Sponges**:
- Boring sponges are known to belong to the genus Cliona. They can bore into substrates like rocks and shells.

5. **Identify the Options**:
- The options provided are:
- a) Cliona
- b) Calina
- c) Euplactella
- d) Hyaluronema

6. **Select the Correct Answer**:
- Since we established that boring sponges belong to the genus Cliona, the correct answer is **a) Cliona**.

### Final Answer:
The boring sponge is **Cliona**.

---