The slanting slab must have been 'sinking' over the years.. used to be able to walk right in the cave some 20 feet inwards . .. with overhead dripping water and even bats flying in and out.
To give you an idea of the size of the 'lubang' or 'hole' in the cliff.. the arrowed show a guy standing there. U can only walk there during low tide.
Sand stone.. see the thin crust brown iron oxide layer weathered and revealed the white harden sandstoneFossils of the burrows of yesteryears marine animal. A common finds over all Miri's sandstone as far inwards as the Canadian Hill.