What are the white exclamation point icons for?

I have circled them in fuchsia in this image.

I have cleared these rooms of enemies, and, as far as I know, completed any intractable objects, so I'm unsure what they represent.

Why does my dungeon map have these icons and what do they represent?

There is a manual in the game menu, which lists these as Dungeon Events, and nothing more.

So I'm unsure if the icons disappears when the event is completed, or if, like the other icons, they remain on the map to denote a location where an event occurred.

Update
Icons will be removed from the dungeon map when they have been completed. Except for permanent icons such as crafting tables and fishing spots.