Source: Pathfinder Society Guide, pg(s). 122
Aeon wyrds, sometimes called ioun wyrds, are wily constructs made of small gemstones, lodestones, granite, and alchemical materials, designed as familiars and conduits for aeon stones. A typical aeon wyrd resembles an earth elemental or paracletus, roughly two feet in diameter and weighs 15–20 pounds. It must be constructed with at least one functional aeon stone, and its aeon stones can be swapped out by any creature it trusts. The aeon wyrd's master benefits from its aeon stones (the aeon wyrd itself never does). Wild aeon wyrds that escaped their masters have been seen in Nex and Thuvia and seek out pretty stones, which they consider to be related to themselves.12