Exspheres (エクスフィア Ekusufia?) are a major element in Tales of Symphonia. Exsphere are Lifeless Beings which are placed onto people in order to enhance their battle capabilities. While it is possible to fight without one, those equipped with Exspheres tend to be much stronger than those without. Cruxis Crystals, such as those worn by the Chosens Collet Brunel and Zelos Wilder, are High Exspheres manufactured via a lost method from the Kharlan War. Chosens are given Cruxis Crystals so that they can be readied as vessels to revive the Godess, Martel Yggdrasill. All sources suggest that they can be used with a normal Key Crest; unless the host develops Chronic Angelus Crystallus Inofficium. Such an occurrence has a 1-in-a-million chance of happening. The disease can be cured with the use of a Rune Crest.

Improperly equipped or malfunctioning Exspheres disrupt the user's mana flow if they are worn too long or removed. This causes the host to transform into an Exebula, as Marble, Alicia Combatir, and Clara do. The use of a Key Crest made from Inhibitor Ore can prevent such an occurrence. Properly equipped Exspheres, such as Presea's, take effect on enhancing a character's abilities, such as Genius's magic, but can also create side effects if the usage is prolonged as seen with Presea's body remaining in a stable state for almost two decades.

Exspheres are mainly mined from Toize Valley in the world of Tethe'alla, in a dormant state, where they are sold to brokers such as Vharley who distribute them to Desians. They are then attached to Humans at a Desian Human Ranch and are awakened to their usable state through the suffering of the human host. Desians manufacture Exspheres as they are necessary to Cruxis's "Age of Lifeless Beings" plan. Lloyd Irving's own mother, Anna, was the host-body for his Exsphere which was a product of the "Angelus Project". Genius Sage inherits Marble's exsphere and Regal Bryan temporarily holds Alicia's. Said project was focused on rediscovering a method for producing Cruxis Crystals. The revelation that Exspheres are awakened using human lives almost causes the party to discard them. But pragmatism wins out in the end and they keep them for the duration of their journey.

At the end of the game, Lloyd makes it his mission to gather up all of the Exspheres in the world to prevent the Lifeless Beings contained within them from being abused, causing harm to people.

In the sequel, Tales of Symphonia: Dawn of the New World, Expsheres have faded from prominence, though the characters from the original continue to use them. Seles Wilder is shown as being much weaker than the girl fought in Meltokio Coliseum due to the fact that she relinquished her Exsphere, as most of Tethe'alla's citizens have, on orders from the King of Tethe'alla. Alice, one of the primary antagonists, uses a machine that runs on Exspheres to control monsters. The Vanguard also mentions that they have gathered all of the Exspheres from the city of Palmacosta. Remnants of the Exspheres are found in Tales of Phantasia.