What are protostomous animals? Give one example.

Explanation

### Step-by-Step Solution:

1. **Definition of Protostomous Animals**:
- Protostomous animals are a group of animals characterized by the developmental process where the blastopore (the first opening that forms during the early stages of embryonic development) develops into the mouth. This is a key feature that distinguishes them from deuterostomes, where the blastopore becomes the anus.

2. **Embryonic Development**:
- During the process of gastrulation, the cells of the embryo undergo a series of divisions and movements. In protostomes, the cleavage is typically spiral and determinate, meaning that the fate of each cell is predetermined early in development.

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