NOTE: I realize that if you have to explain a joke, then it's probably not funny, but here goes anyway. Hardened clay may be regarded as a type of stone, and so in this caption, the implication is that these clay pots originated in the Stone Age and then progressed into the Iron Age, where iron is a type of metal.
Collages, posters, and whimsical pots
NOTE: Hardened clay is a type of stone, so for the sake of this caption, clay begins in the Stone Age. Most nuts, bolts, and similar hardware are made from steel, which is derived from iron. Thus, this image depicts clay pots progressing from the Stone Age to the Iron Age, where they get to wear body piercing jewelry.
Collages, postcards, fun photos, and whimsy
Kathy's original kiln
Wild geese in flight
birds need hens. jelly beans. pergo and coke.