Tropisk plant from Ikea is growing small white pebble-looking things-WHAT ARE THEY?

I got four little plants from ikea for $1.50 each called Tropisk. They are really growing and I've just noticed that they all have these little white things that look like very tiny white pebbles that look soft and spongy like mushrooms. My questions are 1. what are they and 2. are they harmful?