This is a type of sedimentary rock that is formed from from the precipitation of minerals from ocean water or from the breakdown of the shells and bones of sea creatures.

This type of sedimentary rock is commonly known as limestone. The majority of limestone is composed of different crystals of calcium carbonate, these crystals are aragonite and calcite. Limestone is often helpful to historical geologists as limestone still frequently contains fragments of these sea creatures, allowing a glimpse into periods of time from long ago.

The problem of malnutrition in bangladesh is caused in part by "over population."hope my answer has you : )