Creatures of the Eidolon type are usually at least partially composed of the essence (but not necessarily the material) of a particular plane. Some creatures start out as some other type and become Eidolon when they attain a higher (or lower) state of spiritual existence. Many Eidolon have subtypes that reflect which plane of existence they hail from, such as; abberation, air, chaos, earth, evil, fey, fire, good, law, and water. Any Eidolon within their own plane gain the native subtype. Also, any creature (including all Eidolon), gain the extraplanar subtype when they leave their home-plane.