Maggots consume dead or decaying organisms so they are classified as a decomposer.
Decomposition is a process by which organic substances, like leaves or dead animals, are broken down into simpler matter.
A lot of different types of organisms, called the decomposers, will consume the organic substances and continue an essential part of the nutrient cycle. These organisms can be both bacteria, fungi but can also be insects.
This is important for recycling the organic matter that occupies space in the biosphere and that way, continues the movement of energy and matter in ecosystems.
I think verterbrates have a back bone others do not. I only THINK so.
Cell walls are supporting structures that help the plant to have a fixed shape and protect it from injury. Other than that, it helps to keep the plant turgid so that it can stay firm and upright. Because when it enters a high water potential solution, as water moves in, the water exerts turgor pressure on the cell wall and the cell wall thus exerts an opposing pressure to keep water out. Hence cell wall is needed for the plant.
On the other hand, animal cells do not need to keep the structures, as they have the skeletal system to protect the organs and cushion them against any
external injuries.
I hope that helped