The man takes Altin’s copper bit and grins, showing him the pebble, before ceremoniously placing one of three shells over it upon the table he sits at...
Watch the shell carefully, good sir...
The man moves the three shells around in a dizzying display of manual dexterity...
Sleight of Hand 1d20 + 13 ⇒ (15) + 13 = 28 vs Perception checks of onlookers...