Which of the following organisms possess a skeleton made of
calcium bicarbonate ?

Options

A. Meandrina
B. Physalia
C. Adamsia
D. Pennatula

Answer

To solve the question regarding which organism possesses a skeleton made of calcium bicarbonate, we can follow these steps:

### Step 1: Understand the Question
We need to identify which of the given organisms has a skeleton composed of calcium bicarbonate.

### Step 2: Analyze the Options
The options provided are:
1. Mendurina
2. Physalia
3. Adamcia
4. Panatula

### Step 3: Evaluate Each Organism
- **Mendurina**: This organism is known to have a skeleton made of calcium bicarbonate. Therefore, this option is likely correct.

- **Physalia**: This organism, commonly known as the Portuguese man o' war, has a pneumatic skeleton, which means it does not have a skeleton made of calcium bicarbonate. Thus, this option is incorrect.

- **Adamcia**: Also known as sea anemones, these organisms do not possess a skeleton made of calcium bicarbonate. Therefore, this option is also incorrect.

- **Panatula**: Known as sea pens, these organisms do not have a skeleton made of calcium bicarbonate either. Thus, this option is incorrect.

### Step 4: Conclusion
Based on the analysis, the only organism that possesses a skeleton made of calcium bicarbonate is **Mendurina**.

### Final Answer
The correct answer is **Mendurina**.

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