Many potted plants and decorative displays have charcoal in them. Rather large pieces (as seen below) in fact. I asked a friend why all the charcoal, and she said it was to help filter the air. Also, to fight against the dampness that this rainy country can accrue. I’m not sure if any of this is true, but, none the less, they believe it, so I see a lot of charcoal.
This is a decorative display at one of our favorite coffee shops
Notice the charcoal at the base of the plant.