Does it do anything? I know the Spring Sphinx Trinket turns into an arrowhead

According to Subetalodge: Notes: Purchase Autumn Sphinx Relief from the Millionaire Center. Choose the item Autumn Sphinx Trinket and leave in inventory. Plant and harvest a seed from the garden in Veta with the the trinket in your inventory to receive Autumn Sphinx Cuirass

Thank you. I went there to look, but I didn't see notes on the item.

The notes are not on the trinket, just the Cuirass. You would have to search notes to find it.

Oh, good to know for future reference! The trinket was for a pet's TC and I was just curious.