On the very first level, once you are about 2/3 through the level, you will come upon a large rock like structure that is off the ground and has spikes on the underside. You can see the first shiny, near the end of the structure. You cannot jump over this, so you really can’t miss it. Hold
to crouch and go under the spikes and collect the shiny. Just don’t let go of
until you are back out from under this structure. Once collected, you must finish the level and the red badge will fill in with color and the achievement will pop. You cannot quit after collecting, you must finish the level. Thanks to vSully for pointing that out.