Answer:
evolved specialized tubules lined with transport epithelia
Explanation:
The epithelium is a basic tissue that forms a continuous, protective layer of cells. Moreover, transport epithelia are specialized types of epithelium that are involved in the absorption of ions and water from one side to the other of the epithelium, which are responsible for the movement of solutes both in osmoregulation and excretion. During the evolution of excretory organs, higher animals developed specialized tubules associated with transport epithelia whose function is to excrete waste products and selectively retain (filter) nutrients.
I would say photosynthetic bacteria are the most important, because if they disappeared most of the oxygen in the atmosphere wouldnt be here and complex life like humans wouldnt exist
