Final answer:
The materials provided do not contain information about what Aven found buried next to the saguaro cactus, therefore an accurate answer cannot be provided.
Step-by-step explanation:
Aven found a desert tortoise buried in the dirt next to the saguaro cactus. The saguaro cactus has shallow roots that can reach up to 2 meters (7 feet) from the base of the stem, allowing it to gather moisture from rare rainfalls. The cactus also has a large, barrel-shaped stem that can store water. Moreover, it is protected by thorns to prevent thirsty animals from accessing the water inside.
The information provided does not give us a clear answer as to what Aven found buried in the dirt next to the saguaro cactus. It does describe how the saguaro cactus has adapted to survive in the desert by having an extensive root system to gather moisture, a barrel-shaped stem to store water, and thorns to prevent animals from getting to the water inside.
However, it does not mention Aven or what was found buried next to a saguaro cactus specifically. Since there is not enough context or information related to Aven's discovery, it is not possible to provide a correct answer to the question posed.