Answer:
After an organism's soft tissues decay in sediment, the hard parts — particularly the bones — are left behind. Water seeps into the remains, and minerals dissolved in the water seep into the spaces within the remains, where they form crystals. ... If that mold gets filled with other minerals, it becomes a cast.
Explanation:
You would want this observation to be in an area with a lot of biotic and abiotic factors, so the best place for it is an ecosystem.
Zero degrees latitude is the line designating the Equator and divides the Earth into two equal hemispheres (north and south).