Which phylum does this organism belong to? Spiny skinned, radially symmetrical, have tube feet.

Explanation

To determine the phylum to which the described organism belongs, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Key Characteristics**: The organism is described as spiny-skinned, radially symmetrical, and having tube feet.

2. **Understand the Meaning of Each Characteristic**:
- **Spiny-skinned**: This suggests the presence of a tough outer covering, often with spines or ossicles.
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