Other additional plugin-like functionalities, called Layers, are optional and not required to be a valid Marble contract, but do add exceptional capabilities on top of the Marble Core Interface. See the current Layer offerings below:
Named content trackers that can hold any string based content, and also a method to store the content checksum and the algorithm used to produce it.
Named key/value pairs that can be assigned to individual Marble NFTs to represent any kind of numerical value.
A pre-built set of tags and attributes that can be applied to an NFT all at once. Created and updated by group managers.
The Utility Layer adds a handful of useful actions that apply to a broad set of use cases.