The smallest unit of element is

Atoms

An atom is the smallest unit of a pure substance or element that can exist and still retain the properties of the original substance or element. Key concepts: common substances, such as air, water, wood and cloth are mixtures of materials and can be chemically or physically broken down into simpler substances.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

glycolysis is a process that fuel your metabolism. it is apart of cellular respiration the process that produce atp.