Planaria can be cut into pieces, and each piece can regenerate into a complete organism. Cells at the location of the wound site proliferate to form a blastema that will differentiate into new tissues and regenerate the missing parts of the piece of the cut planaria. It’s this feature that gave them the famous designation of being “immortal under the edge of a knife.”

Real-life Grave of the Fireflies
Stoic Japanese orphan, standing at attention having brought his dead younger brother to a cremation pyre, Nagasaki, by Joe O’Donnell 1945. This photograph was taken by an American photojournalist, Joe O’Donnell, in Nagasaki in 1945.

He recently spoke to a Japanese interviewer about this picture:
“I saw a boy about ten years old walking by. He was carrying a baby on his back. In those days in Japan, we often saw children playing with their little brothers or sisters on their backs, but this boy was clearly different. I could see that he had come to this place for a serious reason. He was wearing no shoes. His face was hard. The little head was tipped back as if the baby were fast asleep.

“The boy stood there for five or ten minutes. The men in white masks walked over to him and quietly began to take off the rope that was holding the baby. That is when I saw that the baby was already dead. The men held the body by the hands and feet and placed it on the fire.

“The boy stood there straight without moving, watching the flames. He was biting his lower lip so hard that it shone with blood. The flame burned low like the sun going down. The boy turned around and walked silently away.”