Bestiary

Under the name bestiary comes a medieval book that is a collection of short descriptions of different real or imaginary animals - birds and even rocks that is often accompanied by a moralising explanation.
Bestiaries were popular in the 12th century and were mainly compilations of earlier texts especially the Physiologus?.
Very important part of all bestiaries were illustrations. They added a lot to the descriptions, serving then as an educational tool.
The most important of bestiaries of that time is Aberdeen Bestiary.