In ecology, a food chain can be presented in a pyramid chart. To trace the flow of matter through the ecosystem, one could consider a pyramid of numbers. At the base, which is the widest part of the pyramid, the most organisms in the food chain would be present and would contain the most matter. That level would contain the producers or autotrophs. This level would contain the most organisms in terms of sheer number and thus, the most matter(as well as energy). The level above this, the consumers, specifically herbivores, would have less matter as their numbers would be far less. And, it takes a lot of plant matter, to keep one herbivore alive. So, as you go from the bottom level up to the next level, the number of organisms, continues to go down. The amount of matter will decrease with each level you go up to. The third level in the pyramid would be consumers(carnivores) which would eat the herbivores in the previous level. Again, the amount of carnivores, compared to the herbivores in the level below them, decreases. It would take a lot of herbivores, which are prey to feed one large carnivore. So, as the pyramid continues to the top, the number of organisms in each level decreases, and so does the amount of matter (as well as energy) in that level.