Final answer:
Sea urchins burrow into solid rock for protection from predators and turbulent waters, and their burrowing can shape the ecosystem by creating new niches for other organisms.
Step-by-step explanation:
The burrowing behavior of sea urchins serves multiple ecological purposes. By burrowing into solid rock, sea urchins create shelter for themselves, which offers protection from predators and turbulent water currents. Furthermore, this burrowing can contribute to the shaping of the ecosystem, as it alters the physical structure of the habitat, potentially creating new niches for other organisms. The sharp spines of the sea urchins protect them during the burrowing process and deter predators.