The layer inside earth that creates earth's magnetosphere is the

Outer Core of Earth

Explanation:

The outer layer of core of earth consists of iron as a major constituent. Due to internal high temperature and low pressure (as compared to the inner core) , the iron in this layer exists as liquid iron. Since the earth is rotating continuously on its axis, the liquid iron is also rotating thereby producing magnetic field. Due to magnetic field , this sphere of earth is known as magnetosphere.

yes its like the dead sea which is full of salt which makes you stay afloat

so yes an egg will float in salt