Rocks. Big rocks.
Anytime you go somewhere new, or someone says, “I’m going to XXXX, do you want me to bring you anything?” Ask for rocks.
Every trip for about a decade we did this for the Westie with Jaws of Might. Rocks were the only thing that ‘lasted’. Rocks from different places, smelling and tasting of different things.
No rocks were removed from protected wild life areas on eco-vacations.