Bag of Nourishing Crunch Rocks

Inside a small red satin pouch with a golden rope tied in a bow, contains a handful of colourful gem-like rocks of various colours; red, blue, green, amber, magenta. 

Each rock, though very crunchy, provides enough sustenance and nourishment to cover one meal. After eating, you must roll 1d4. If the die lands on 1 or 4, you take the corresponding number of piercing damage from the shards of rocks sliding down your throat. There are 1d12 + 6 gems inside the pouch (to be rolled on purchase).