Answer: It is a pyramid shape because the trophic pyramid, is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem.
The bottom of the pyramid is made up of plants and other organisms that perform photosynthesis. Photosynthesis transforms energy from the Sun into usable energy for living things. An ecosystem needs to have more of these organisms than any other organism because they provide energy for the entire ecosystem.