Well the soil classification is usually done on the basis of particle sizes and composition of soil.
<span>Clay </span>usually consists of particles less than 0.075 mm in size. It is a sticky soil and shows great changes in volume with variation in its water contact. It also shows considerable strength when air dried.
<span>Silt </span>has larger particles than clay and are mainly inorganic in nature. The particle size is less than 0.075mm and exhibits slightly plastic or non plastic behaviour.
Humus is soil consisting of dead and decaying organic matter. It is mainly organic in content but some inorganic particles may be mixed in it. The top soil in a tropical forest may be considered as humus.
This is beneficial and is actually an adaptation of humans to climates with larger amounts of sunshine. The darker color of skin helps prevent damage such as sun burn.
The mantle i think sorry if i am wrong
Both plants and animals have these. It is a eukaryotic cell.