When the word "SEEK" is displayed on the bottom left corner of the screen, that means there's something important to be found somewhere in the immediate vicinity. Press the Z Button to look around, and see if you can find it!

If you manage to focus on an item dropped on the floor, sometimes the word "SEEK" will immediately be displayed again. If you can skillfully complete a streak of such discoveries, you may be able to obtain rarer items as a result.