Sponges are the simplest structure and the most primitive form among multicellular animals. They have appeared before the Cambrian and have continued to thrive until modern times. Sponges evolved from single-celled animals. Their cells have differentiated but have not yet formed tissues and o...
All living objects in nature are called organisms. Generally speaking, living things can be divided into three categories: plants, animals and microorganisms. Starfish - an echinoderm There are approximately more than 300,000 known species of plants, which can b...