You are shooting the black plaque on the far wall of the secret rooms. It will turn into a symbol that is either on or not on your totem. If it’s a wrong symbol, be sure to shoot if “off” again. If it’s a right one, leave it up.
Selected
Unselected
First Room. Right after you drop down after the totem, there will be a hidden room if you turn around.Second room. In the room with all the frozen things in blocks, there’s a room in one of the corners opposite from the way you’d normally go to the encounter.Third room. This is in the first encounter room at the bulbous end of the giant wishbone up high. It opens an elevated door to your left.Fourth room. Before the second encounter in the Collection area, a shard up high will open a door lower for another shot at the symbol.Fifth room. In the final stand area for the Caretaker, a darkness shard will open up a door not next to it, but across the room behind you.Sixth room. After the caretake in the first room with enemies during the jump puzzle on the left side.Seventh room. This is in the room just after the second secret chest.Eighth room. After Upended you go toward the left stairs, go past the statues and the crystal is floating in the air.Ninth room. Immediately before the final boss. On the top floor the darkness shard is floating behind you across from the boss area. Door on the right.