This undifferentiated embryonic structure then undergoes a phase of major cell migration called gastrulation, producing a gastrula with three separate germ layers: the endoderm, mesoderm, and ectoderm. Endoderm The endoderm is formed from cells that migrate toward the center of the developing gastrula.
The Eiffel tower is made of puddled iron. It is made up of steel in steel X's. The Eiffel Tower is made of iron. The Eiffel Tower is made of pure iron.
1 The tower was built to sway slightly in the wind, but the sun affects the tower more. As the sun-facing side of the tower heats up, the top moves as much as 7 inches (18 centimeters) away from the sun. 2  The sun also causes the tower to grow about 6 inches.  The Eiffel Tower weighs 10,000 tons.