How do you think fossils form?

An animal, such as a dinosaur, dies and falls to the bottom of a riverbed.

or

The flesh of the animal rots away or is eaten by smaller creatures, leaving only the bones (skeleton) behind.

littering streams           is the answer

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.