Characteristics. 1  Closed pockets of tissue that can be filled with fluid or pus. 2  Can appear anywhere on the skin. 3  Smooth to the touch; feels like a pea underneath the surface. 4  Slow growing and generally is painless and benign. 5  Only needs attention if it becomes infected or inflamed.
It has long been recognized and documented that insects are the most diverse group of organisms, meaning that the numbers of species of insects are more than any other group. In the world, some 900 thousand different kinds of living insects are known. This representation approximates 80 percent of the world's species. The true figure of living species of insects can only be estimated from present and past studies.
It is estimated that around 9 or 10 million species of animals inhabit the earth; the exact number is not known and all estimates are rough. Animals range in size from no more than a few cells to organisms weighing many tons, such as the giant squid. By far most species of animals are insects, with groups such as mollusks, crustaceans, and nematodes also being especially diverse. By this measure our own group, the vertebrates, is relatively inconsequential from a diversity perspective. All animals are members of the Kingdom Animalia, also called Metazoa.