The beach rocks I use are basically Sandstone,and the other rocks I use are called Mexican Pebbles which are very smooth and leave a nice finish.This week's rock is a nice round Sandstone I call a "Spinner Rock" because when I flip it upside down and give it a twirl,it spins for a while on a blue bobble which was adhered to the top of the rock.I don't usually paint my rocks yellow unless I want to have it serve another purpose.In this case, it can be used as a top or just as a beacon to direct oneself to the restroom in the middle of the night!Always make sure the rocks have been "Charged"( i.e. held under a regular lamp for about a minute) before you turn out the light on your nightstand.