Well there are many but the surface of the earth is the material violin one outer core (if that makes sense
When sound waves hit a solid surface they either reflect, refract, or absorb.
Echo's are caused by the reflection of sound waves.
Answer: solar energy
Explanation: Solar energy causes a great impact on plants and animals. Plants need sunlight to grow and if we dont have it then animals wont be fead and we would not be fead. Solar energy literally is the most important thin because without it we would be dead
I hope this helps a thanks and a brainlist would be greatly appreciated :)