Ribosomes, mitochondria, ER and chloroplast.
The ecological pyramid is smaller at the top due to the lower amount of species to fit into the category (diversity is decreased, and the higher, the more suppressed the energy is in the animals/species).
Cell specialization allows new cells to develop into a range of different tissues, all of which work together to make living organisms function as a whole. The process of cell specialization exactly how cells develop into their diverse forms is complex.
