Word for an object that alters the course of your life?

When learning about people, either through biographic readings or in person, I'm very interested to learn which "object" has had the single greatest effect on them. For example, what has made an indelible mark that changed their life, or "altered the colour of [their] mind", or imputed unto them a goal or a passion they've been chasing ever since. I suppose a person can have more than one of these objects, but we usually have only one for any given context.

These type of objects are usually books or music albums, and I want to know which of them are esteemed in this way, because those are exactly the objects I want to add to my personal collection.

I liked "lodestar" for a bit, but it implies an everlasting guide that one can reliably call upon, or to extend the metaphor, implies something that one still necessarily believes in.

When I think of books and albums that really have an effect on someone, I think they're transformational. Is that what you're going for?

You can consider influence as a single word.

a person or thing that affects someone or something in an important way [MW]

Example:

Livingstone’s interest in science and nature led him to investigate the relationship between religion and science and in 1832 he read Philosophy of a Future State by science teacher and minister Thomas Dick. The book was a big influence on him and helped reconcile his faith and science.

[heraldscotland.com]

However, the usual phrase is life-changing < something >.

life-changing: (adj) having an effect that is strong enough to change someone's life [Cambridge]

For example, goodreads.com has a section called "life changing book lists".

Perhaps seminal as the ellipsis of the phrase seminal event.

Fetish in its technical sense from social science is close. It captures the idea of an object carrying symbolic importance. The sexual connotation accumulated through contemporary common use may or may not cater to the kink of a particular communication.

Juju's metaphysical flexibility makes it about perfect, and extends naturally to collections via juju bag. But only if we are willing to step abroad from European word origins so far as to set foot in Africa.

Personally, I like the Ojibwa totem even though using it in the context of the personal rather than that of a community is perhaps a bit of legacy "me" generation narcissism. Like juju, totem captures the idea of collection and totems points to the collection rather than their container. But what I really like is that totem as a carved pole conveys ideas about order among and dependencies between the items.