At least part of the adaptive immune system is implemented in the thymus. As an infant, the thymus makes examples of nearly every type of cell in the body and uses it as negative labelled examples to tune the false positive detector so it doesn't identify self as threat. From an information theory perspective, that's pretty extraordinary (you don't normally expect differentiated cells in an organ to act like cells from another organ).

Another part of the adaptive immune system randomly shuffles different regions of genes together to produce enormous diversity (searching for a rare example of something that "works"), then picks the proteins from those genes that work best and distributes them throughout the body.

Pretty amazing stuff.