What occurs in the process of photosynthesis?

I'm not sure how in depth of an answer you need here, but it uses sunlight (or energy from sunlight) to create food (Sugar is the food I think) from carbon dioxide and water. But that is the basics of what happens in Photosynthesis. 

Carbon dioxide and water then sunlight which makes glucose and chlorophyll

Although i don't know what is the simulated system, starfish are predators that eat mostly  microalgae,  snails, sponges, bivalves, mussels and other small marine animals. removing starfish from any system would definitely increase this animals that they prey.