Which of the following statements is correct for sponges without exception?

Options

A. They all have calcareous spicules
B. They have high regenerative power
C. They are found only in marine water
D. They are all radially symmetrical

Explanation

To determine which statement is correct for sponges without exception, we need to analyze each of the given statements about sponges.

### Step-by-Step Solution:

1. **Evaluate the first statement:** "They all have calcareous spicules."
- Sponges can have different types of spicules. They can be made of calcium carbonate (calcareous), silica, or spongin fibers. Therefore, this statement is **not true** for all sponges.

2. **Evaluate the second statement:** "They have higher regeneration power."
- Sponges are known for their remarkable ability to regenerate. They can reproduce asexually through processes like fragmentation and gemmulation. This statement is **true**.

3. **Evaluate the third statement:** "They are found only in marine water."
- While many sponges are marine, there are also freshwater species, such as Spongilla. Thus, this statement is **incorrect**.

4. **Evaluate the fourth statement:** "They are all radial symmetrical."
- Most sponges are asymmetrical, and while some may exhibit radial symmetry, it is not true for all. Therefore, this statement is also **incorrect**.

### Conclusion:
The only statement that holds true for all sponges is that they have higher regeneration power.

**Final Answer:** They have higher regeneration power.