Answer:
In biology, symbiotic nitrogen-fixing bacteria invade the root hairs of host plants where increment or multiply and stimulate formation of root nodules, enlargements of plant cells and bacteria in intimate association. The bacteria that change nitrogen gas from the atmosphere into solid nitrogen usable by plants are called nitrogen-fixing bacteria. These bacteria are found both in the soil and in symbiotic relationship with plants.
Explanation:
The rock layer on the bottom will decompose and either turn to sand, gravel, or blend in with the dirt (but most likely not the last one).
