Emblems

Emblems take the form of a symbol that appears on the body of the user after "consuming" a "Fossil". The location on the body varies, depending on where the user would associate with the "origin" of the power (for example; The Heart - because that's what they view as the centre of their body/circulatory system; Hands - a practical person may first think of using their hands to "cast" the ability, placing the Emblem there).
Moulding: A key mechanic of Emblems is the ability to "mould" the Emblem's shape. This allows the user to extend and grow the Emblem from its original position around their body. Depending on the shape, location and size of these, different effects can occur.
Emblems fit into three broad categories: Within Body, Placement and Domain
1. Within Body: Types - Production (Blue), Absorption (Green), Influence (Red)
These emblems all occur on and/or within the body of the user. Production types release substances from the users body. Absorption types draw substances from the environment into the body to act as a "power source" to improve natural abilities of the body. Influence types allow the user to control an aspect of their body at will.
Examples: Production - Bubbles; the user can give off bubbles from whereever their Emblem is located on thier body. Absorption - Fire; the user can draw fire into their Emblem (turning it into "stored" energy). They can then "spend" this to increase a natural ability (i.e. increased healing, more strength, improved healing, etc.). Once they've used this, they need to draw more of the substnace in to use again. Influence - Heat; the user can increase or decrease the temperature of whatever body part their Emblem is on. They can extend this to/through non-living substances their Emblem is in contact with (however this depends on the property of the substance)
2. Placement: Types - Base (Black on white background) and Alteration (White on black background)
These Emblems allow the user to "place" a copy of their Emblem onto an object. This will then create an effect on the object depending on the Placement type and the Embelms core ability. Alteration types change the properties of the object they are on. Base types emit a property from them, and use the object they are placed on as a "canvas"
Examples: Base - Camera; after placing their Emblem on an object, the user can see through each one, like looking through different channels on a security camera. Alteration - Orbital; after placing their Emblem on an object, the Emblem overides the objects "gravity" and makes the Emblem user their new centre of gravity. The objects will proceed to orbit the user in a manner similar to starts and planets.
3. Domain (Purple):
Domain type Emblems are placed onto the "world" - typically extending out from the user, with them acting as the centre. Domain types overlay a new "law" or "rule" of the universe/physics onto the world. There are no set standards - it could be as simple as "the user has complete manipulation over water within the Domain" or as complex as bringing a game to "life." These are the rarest abilites and subsequently least explored/understood in universe. However, what is known is that, once placed, they cannot be moved and the user cannot leave the Domain until they withdraw it (though can move around inside it).

Manifestation

Emblems as a base could be mistaken for a marking or tatoo on the body. While exact looks vary, they typically have a standard form of a "centre," an "inner" layer and an "outer" layer. This "outer" layer is what users can "mould" to spread over their bodies (as opposed to the "centre" that always stays in place).
Colour: Each type of Emblem has its own specific colour; Within Body: Types - Production (Blue), Absorption (Green), Influence (Red) Placement: Types - Base (Black on white background) and Alteration (White on black background) Domain: Purple

Source

Emblems are a protective reaction of the body, drawn out by the presence of "fossils" within it - similar to an immune reaction. Subsequnetly, the Emblems are powered by a persons body and require energy from them to function. However, the amount needed is realatively low, so while in theory a person could exhaust themselves using an Emblem, they are more likely to physcially or mentally exhaust themselves long before.
Usually a nights sleep and a good meal is enough to restore the person's energy enough to get a full days use again (at the least).

Discovery

Emblems are found in the earliest known historical recording in the world - to the point of being the basis of written language - though it is also known that there is a long history before this recording, with Emblems also being present there. Subsequently, no one knows who "discovered" it, just that they have existed as far back as they can track.
Emblems are prominent in history - being mentioned or referenced in many recounts of legends and events.

Gestures & Ritual

Emblems are controlled mentally, moudling and creating the effect comes entirely from mental control. However, this can be difficult to do when focused on other tasks (such as during a fight) - like tapping your head and rubbing your stomach simultaneously. Subsequently, many users train to create habits they associate with different uses of their Emblems to make this easier.
Habits: The most common habit used is Verbal - assigning a name to a certain use/technique/move of an Emblem allows the user to perform the technique by saying the name. This makes the technique easier for the brain to process, as they perform the move subcounciously while the concious mind focuses on other actions.
Verbal is the easiest habit to train, as it is removed from physical action, but non-verbal methods such as gestures are often employed.
High level Emblem users are often able to perform actions without relying on habits - though this is relatively rare as many come to rely on these habits and never refine their technique further (though many will be able to use basic techniques they have lots of experience with non-verbally).
Typically, how reliant an Emblem user is on habits to use techniques correlates to their level of skill.

Applied Restriction

The main limit on Emblem use is physicality. As a baseline, the user is still a person, so can only perform within the limit of thier body. For example, shooting force in one direction will create recoil in the other - if the user cannot withstand this they will suffer the expected effects.