The Illlai was the basic currency unit of the Federation of Eniam. The word origin was lost to time. As of 1,138 BBY Illlais were in the form of filed-down lumps of crystal with specific marks cut in them. The Eniamo had basic forges then, but these were reserved for emergency weapons.
The Illlai had several variations that were worth different quantities, including the Wriilllai, which was worth five Illlai, and the Yari, which was worth 1/5 of an Illlai. When the Arrnilioh became the official planetary currency, use of the Illlai ceased.