In the years before the advent of arcanotechnology and dimensional fatigue events, teratology was the study of abnormalities and biological deformations. In the wake of the second renaissance, it became the study of exomorphs, extradimensional entities, and most prominently, teratomorphs, more commonly and vulgarly known as kaiju.
The PCs discover a large white ball in the branches of a tree, or in a niche in a cave. Unless magically examined, or by a PC with a specialty in insects, it is a plain, smooth white ball. After a short time, it hatches and releases hundreds of spiders, cockroaches, some other nasty bug