Whats this red sparkle in the Royal Records Room?

[Sheggs2]

Whenever I load this level (standard mode, not ng+) theres a little red sparkle in one corner and it makes a chime sound but I don't understand what its for. It shows up in other levels in different spots too.

[Wisp]

You have the Book of Secrets equipped. When wielded it makes cutscenes or battlefieds with 'secrets' hidden in them glint red. You're meant to puzzle out what the secret might be and input it into a strange area of rocks and teeth later in the game.

It could be something like letters in background art to be translated, or it could be a code on the battlefield. Basically a bonus puzzle game hidden inside of your TDRPG.