A stream of liquid sand flows from above and reacts with your shadow as if
it were solid. Its hypnotic motion conjures childhood feelings of playing
with water or building wet sandcastles. Like
making shadow puppets, you can easily construct concave structures with your
hands to catch the sand and then you can pour it from hand to hand or maybe
into your friend's mouth.
Play with it long enough and you might discover some of its many secrets.
(Hint: Makes reference to
"The Rainbow Goblins" by Ul De Rico).