Even though Rub Al Khali is extremely arid, but there is still room for some flora and fauna to survive...
There is water in some parts of the desert that allows the dwellers to farm plants such as wheat alongside the water source. Wheat is extremely useful for growing flour and creating rice and bread.
The Rub Al Khali is too arid for any animal to survive except for camels and arachnids. The domestic Arab and Egyptian camel are able to travel throughout Rub Al Khali for long distances with weight and without water. They provide a decent and efficient transport.
Many arachnids roam the Rub Al Khali; the most common and well known being the camel spider. It is slightly larger than a tea cup and lives for less than a year in the wild. It is not deadly to humans, but its bite is painful. They can reach chasing speeds up to 16 km an hour and have their diet set on scorpions and birds around the borders of Rub Al Khali.