Nature works like a system, with many parts helping each other. Sea turtles are important to the environment. The author supports the point with reasons: they help keep seagrass beds healthy and healthy seagrass supports many animals. Strong evidence is given: At one local site, scientists observed for 17 days and recorded 15 examples of this role. A weaker support is: One visitor wrote, “Sea turtles are amazing,” but did not explain how they help. One extra detail is: Some rocks are smooth and some are rough.