The remains of fossils give scientists clues as to what the world may have been like a long tome ago. If fish fossils are found on the side of a mountain, there may have been a lake there. If a skeleton is found, they can decide what creature it was.
Breakwaters protect an anchorage from the effects of weather and longshore drift, while jetties protect against erosion, by keeping the waves from sweeping the sand away. Difference, they both protect against different things.
The connective tissue is among the four major classes of the tissue. It is the most widely distributed and the most abundant class of the tissues. However, the type of tissue in every organ varies. Composed of cells, fibers and matrix, this type of tissue is different in different organs of the body.
The variability in it's type is provided by the difference in the degree of the order of the cells, fibers, and the matrix. This variability contributes to the diversity of this tissue.
Hence, the blank can be filled with 'diversity'.
Bivalves are abundant and important parts of reefs.