Introduction:
The functional unit of an ecosystem refers to the components and processes that contribute to the functioning and productivity of the ecosystem. It includes various aspects such as productivity, decomposition, and energy flow. However, ecological pyramids are not considered a component of the functional unit of an ecosystem.

Explanation:
Ecological pyramids are graphical representations that depict the trophic levels and the flow of energy, biomass, or numbers in an ecosystem. It represents the relationship between different organisms in terms of their energy or biomass transfer. However, ecological pyramids are not considered a component of the functional unit of an ecosystem. Here's why:

1. Productivity:
- Productivity is the rate at which energy is captured and stored by organisms in an ecosystem through photosynthesis or chemosynthesis.
- It represents the amount of biomass or organic matter produced by plants or autotrophs in an ecosystem.
- Productivity is a crucial component of the functional unit as it determines the energy available for other organisms in the ecosystem.

2. Decomposition:
- Decomposition is the breakdown of organic matter by decomposers, primarily bacteria and fungi.
- It plays a vital role in nutrient cycling as decomposers break down complex organic compounds into simpler forms that can be reused by plants.
- Decomposition is an essential process in the functional unit of an ecosystem as it releases nutrients back into the ecosystem.

3. Energy Flow:
- Energy flow refers to the transfer of energy from one organism to another in an ecosystem.
- It follows the trophic levels, where energy is transferred from producers (plants) to primary consumers (herbivores) to secondary consumers (carnivores) and so on.
- Energy flow is a fundamental aspect of the functional unit as it determines the flow of energy through different trophic levels.

4. Ecological Pyramids:
- Ecological pyramids are graphical representations of the trophic structure and energy flow in an ecosystem.
- They represent the transfer of energy, biomass, or numbers from one trophic level to the next.
- Ecological pyramids provide a visual representation of the ecosystem's structure but are not considered a component of the functional unit of an ecosystem.

Conclusion:
In conclusion, while productivity, decomposition, and energy flow are important components of the functional unit of an ecosystem, ecological pyramids are not considered a component. Ecological pyramids serve as visual tools to represent the trophic structure and energy flow but do not contribute directly to the functioning of the ecosystem.