This app lets you view .caar files.

CAAR files are Core Animation Archive files. They consist of core animation layers that are archived using NSKeyedArchiver to be later used as vector images in UI elements (especially when there are animations involved).

Core Animation files are used by Apple in several system frameworks and having a way to view them can lead to some interesting discoveries 🙃

The app also embeds a QuickLook plug-in that can generate thumbnails/previews of caar files.

This is a very hacky and quick tool I made for myself. Some .caar files have proprietary classes encoded in them that can't be read by 3rd parties, if you have a caar file that can't be viewed with this app, that's probably the cause.