What was the Tree of the Knowledge of Good and Evil?

The Garden of Eden was a beautiful paradise that could provide everything that Adam, Eve and the animals needed for daily survival.  God allowed them to eat from the fruit of all of the trees except for one, the Tree of the Knowledge of Good and Evil (Gen 2:17).  When the Fall of Man happened, both Adam and Eve ate some fruit from this tree.  We don’t know what the fruit looked like and it is not very important, but what is important are the results of Adam’s rebellion.  They disobeyed God through an act of rebellion thus resulting in death and suffering to enter the world, which affected both Adam and Eve and all of their descendants.