Each year, earthworms move deep into soil during fall and winter and return toward spring and summer. The likely stimulis for this behavioral response are relative humidity & temperature. Since the nematode breathes via the skin, the mucus coating may become dry & the organism would die if exposed to extreme cold & dryness.
There is an outer core and an inner core. The outer core is extremely hot and is made mostly of molten (or melted) iron, which is called magma. It is about 1300 miles thick
