Sometimes it shows up randomly on my minimap when I’m moving around, sometimes it seems like it’s been there for a while. I have no clue what this symbol means — there’s no legend to tell me what it means, and the main map doesn’t show them.
Sometimes it’s not clear what exactly it’s trying to indicate, for example:
I’m facing the star icon, the fov is pointed towards it, but there’s nothing on the screen
These are the collectible items which you can turn into the Statues of the Seven.
They are different depending on the region you are in.
You can gather them and then devote them to any statue you find for increased stamina, adventure exp and other rewards
Sometimes they are hidden, and might require smashing rocks, exploding something or climbing up trees etc.
The example given in the question, I would attack the three piled rocks with a claymore.