Tenho certeza que este é o conto Um planeta chamado Shayol por Cordwainer Smith.
Começa com um novo prisioneiro, Mercer, sendo preparado para o planeta prisão Shayol por ter sua pele endurecida em um centro médico em um satélite. Um dos médicos diz a ele o que está reservado para ele.
"There is an attendant. He is a man, but not a human being. He is a homunculus fashioned out of cattle material. He is intelligent and very conscientious. You specimens are turned loose on the surface of Shayol. The dromozoa are a special life-form there. When they settle in your body, B'dikkat - that's the attendant - carves them out with an anaesthetic and sends them up here We freeze the tissue cultures, and they are compatible with almost any kind of oxygen-based life. Half the surgical repair you see in the whole universe comes out of buds that we ship from here."
Quando Mercer olha pela primeira vez na superfície, ele vê
...an enormous human foot, the height of a six-storey bulding.
"But It can't be a real foot," said Mercer.
"It is," said B'dikkat. "That's Go-Captain Alvarez, the man who found this planet. After six hundred years he's still in fine shape. Of course he's mostly dromozootic by now, but I think there is some human consciousness inside him."
Como um aparte, uma das antologias que contém esta história ( Spectrum 4 ), apresenta como capa.