Structures which help in osmoregulation and excretion in flatworms are called.

Answer

To answer the question regarding the structures that assist in osmoregulation and excretion in flatworms, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organism**: The question refers to flatworms, which belong to the phylum Platyhelminthes.

2. **Understand the Characteristics of Flatworms**: Flatworms are bilaterally symmetrical and triploblastic organisms, meaning they have three germ layers.

3. **Recognize the Importance of Osmoregulation and Excretion**: Osmoregulation is the process by which organisms regulate the balance of water and salts in their bodies, while excretion is the removal of waste products.

4. **Identify the Specialized Structures**: In flatworms, there are specialized cells known as flame cells that play a crucial role in both osmoregulation and excretion.

5. **Conclude the Answer**: Therefore, the structures that help in osmoregulation and excretion in flatworms are called flame cells.

### Final Answer:
The structures which help in osmoregulation and excretion in flatworms are called **flame cells**.

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