They help us think about the movement of energy and matter not only in individual marine organisms but also in oceanic ecosystems. They also give us a starting point for considering whether our own planet is a living organism, as proposed by James Lovelock in the Gaia hypothesis. Living matter is organized into complex structures based on organic molecules. Think about the organization of living things. Living matter maintains some type of homeostasis.
Homeostasis is the maintenance of relatively constant internal conditions.
Our bodies accomplish this through a series of biofeedback mechanisms, such as shivering when it's cold or sweating when it's warm. Animals such as lizards lie in the sun or the shade to maintain a relatively constant temperature. Not all life regulates temperature, but other properties are regulated, such as their chemical composition, the amount of water in their bodies, their salt content, etc. Crystals and other non-living things don't readily maintain internal conditions. Living matter grows and develops.