The primary currency of Stygia, an obolus (pl. oboli) is a grayish soulsteel disk approximately 4 inches in diameter and marked with the seal of Charon. Each obolus is comprised of one soul, no more or less. The value of the obolus is inherent in the soul itself. An obolus is a valuable unit of currency, and wraiths will often halve or quarter the coin for trade purposes - oboli will reassemble if left alone, and most wraiths prefer not to think about the division and reassembly of souls.