Name a unicelluar plant which is several cm long.

Explanation

**Step-by-Step Solution:**

1. **Understanding Unicellular Plants**: First, we need to clarify what a unicellular plant is. Unicellular plants are organisms that consist of a single cell. They belong to the plant kingdom and are often categorized under algae.

2. **Identifying Long Unicellular Plants**: The question specifically asks for a unicellular plant that is several centimeters long. While most unicellular organisms are microscopic, some algae can grow to significant lengths.

3. **Researching Examples**: Among the various types of algae, we need to find one that fits the criteria of being unicellular and several centimeters long.

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