A text icon with its corner folded

I found a text icon on the binder pane had its upper right corner folded, unlike other text icons. Does anyone know what is the difference? I don’t think the text block tagged with the peculiar icon is not different from other text blocks.
text_icon.png

The folded corner indicates the document has a snapshot, i.e. a saved earlier version of the document. If you load the document in the editor and choose Documents > Snapshots > Show Snapshots, the inspector will show you the snapshots along with the times they were taken; clicking one will show the text in the lower section of the inspector. You can create new snapshots here as well, with the “+” button, delete a snapshot by selecting it and clicking the “-” button, and you can “roll back” to a snapshot as well, replacing the current version of the document with the text of the selected snapshot. Scrivener will give you a chance to create a new snapshot of your current version before reverting to the snapshot, just in case you want to go back.

Thank you very much, MimeticMouton! I forgot I created a snapshot days ago.