It's Head Shot Week, as announced yesterday.
I give you paired mirror-image bird heads, inscribed on Tridacna gigas (Giant Clam) shell. The plate is part of a necklace that came into my hands at Lau Lagoon, Malaita, Solomon Islands, in 1968.
I asked about the black substance in the scribings, thinking it was something like charcoal mixed with a binder. Answer: shoe polish. Explanation: it's easier. I asked why the necklace wasn't strung with fiber. Answer: fishing line doesn't break.
Material culture is always changing, everywhere. The Lau used new materials when they judged them superior.