List any three characteristics of microorganisms.

Explanation

**Step-by-Step Solution:**

1. **Definition of Microorganisms**: Microorganisms are tiny living organisms that cannot be seen with the naked eye. They include bacteria, fungi, yeast, and viruses.

2. **Characteristic 1 - Ubiquitous Nature**: Microorganisms are found everywhere in the environment. They can thrive in various habitats such as soil, air, and water, and can even survive in extreme conditions like high temperatures, low temperatures, high pressure, acidic environments, and high salt concentrations.

3. **Characteristic 2 - Size**: Microorganisms are extremely small, which is why they cannot be seen without the aid of a microscope. Their microscopic size allows them to occupy diverse ecological niches.

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