Bag of Infernal pebbles

This magic items is a bag that contains 15 constantly lit, molten pebbles. Any one may come in contact with the bag with no side effects. If a non-attuned creature comes in contact with the pebbles, deal 1d4 fire damage and an additional 1d4 fire damage at the end of their turn for 2 turns. The pebbles may create a small flame upon coming in contact with a flammable surface. A pebble gets consumed upon coming in contact with anything that is not attuned nor the bag of infernal pebbles.

Notes: Damage: Fire, No more than 15 pebbles in the bag, Tiefling, fire dragon born, fire genasi race only