The researchers studied different types of sea creatures living on hard surfaces in the South Atlantic. They used different tools to collect samples and found that the types of creatures changed depending on the depth of the water. Sponges were the most common creatures in deeper areas, while smaller creatures like worms and shrimp were more common in shallower areas. The number of species was higher in the middle of the shelf compared to the inner and outer areas. The researchers also found that the diversity of creatures was due to many rare species living in the area. Overall, depth seemed to be more important than season or location in determining the types of creatures found.