First image of Mycobacterium avium "copyright Dennis Kunkel"
Souls are everywhere on earth because every living entity is alive due to an animating principle within, a soul. The great variety of microscopic organisms, plants, insects, snakes and mammals, all are animated by invisible principles of life which organize their being with certain abilities to relate to the environment enabling them to grow, move and reproduce.
Are animal souls immaterial?
Daniel Povinelli, a comparative psychologist at the University of Louisiana raises an interesting question: "If apes can count, use tools, and learn sign language like humans, can they think like us too? If so, why don't they study us like we them?" His answer, "Because they do not think about thinking." Further, animals do not have a freedom to choose between good and evil and are unaware of the mysterious presence we call God. This seems to indicate that the animal soul is bound up within the limitations of energy/matter and limited to awareness only of this world. Their souls may very well be composed of refined matter of a high energy level.
How do we know the human soul is immaterial?
Look at the plant life animation. Our eyes and imagination can only receive concrete images.
Our soul/mind derives from these images the concept of plant-life, life forms which use solar energy and the earth environment to grow and reproduce. I can see and touch many individual trees but I cannot see or touch plant life. Only the immaterial soul can grasp this universal concept.