A hybrid monster from the Luttrell Psalter, c.1325-35.
from Monsters and Grotesques in Medieval Manuscripts,
Alixe Bovey, University of Toronto Press and The British Library, 2002.
Grotesques and gargoyles flourish abundantly in nearly all forms of medieval art.
Both Gabriele (Germany) and Sam ( France) have posted pictures of those and other more natural animals that decorate various pillars, cornices and pediments of some of the ancient structures to which they have access, and which have survived reconstruction, mutilation, architectural taste, and time.
Back on October 2, Yahoo News included an AFP story about a gargoyle mystery.
Seems a series of grotesque stone faces began appearing nocturnally beside public places in Yorkshire, England. The heads were eventually traced to artist/sculptor who deked by in the dead of night - but not before they garnered nationwide media attention.
A very neat exercise in promotion: create a mystery, acquire attention for one's work.
This technique could be adapted to some books and sometimes has, though a specific example escapes me at the moment.
Certainly the effort has longer legs than buttons and bookmarks and black swan hats.
The symbolic objects of interest should be visible, unusual, non-threatening. -- and, most of all, mysterious.
Probably various other restrictions/characteristics apply. Size? Fragility?
My imagination fails me at the moment for any of my own stuff, but it doesn't hurt for anyone to speculate just how one might arrange a similar promotion.
Could you conceptualize your book this way?