This chest ornament is of cast brass and is from the Konyak Naga people. It is in the form of a segment of conch or chank shell with a fish-tail terminal. The top has been decorated with a zig-zag border and two loops to allow suspension.
Such items were male prestige ornaments and might have been worn by warriors who had successfully taken heads.
See a related example in Jacobs (1990, p. 255).
The example here has a fine patina and obvious age. It is stable and wearable.
Borel, F., The Splendour of Ethnic Jewelry: From the Colette and Jean-Pierre Ghysels Collection, Thames & Hudson, 1994.
Daalder, T., Ethnic Jewellery and Adornment: Australia, Oceania, Asia, Africa, Ethnic Art Press/Macmillan, 2009.
Jacobs, J., The Nagas: Hill Peoples of Northeast India, Thames & Hudson, 1990.
Schmitt, K., ‘The language of Naga ornament: Beads, Bones and Hornbill feathers’, Arts of Asia, July-August 2004.