Apply a 25px Gaussian Blur to the city layer (Filter > Blur > Gaussian Blur) so it won't distract us from the main element – the metal apple.
Turn off the visibility of the city layer and using the pen tool carefully make a selection like the one shown below. After that feather the selection by choosing Select > Modify > Feather and entering 2px in the dialog box.
Turn the visibility of the city layer back on and add a layer mask by choosing Layer > Layer Mask > Reveal All. Press D to set default colors and press Ctrl + Backspace to fill with black, Ctrl + D to deselect and Ctrl + I to invert. You should have the city placed nicely behind the apples and in the process we also made something that resembles a corner (in the right of the image).
To add some realism to our scene let's add an apple worm to the metallic apple. First let's make the hole. Select the Elliptical Marquee Tool and Hold shift while dragging to make a perfect circle. Create a new layer (Ctrl + Shift + Alt + N) and fill this selection with any color you want (press Alt + Backspace).
Double-click this layer you just created and drag the Fill slider all the way to the left. Add some Inner Shadow, Inner Glow and Color Overlay.
Open file "Worm" and using the Quick Selection tool make a selection of the worm. Press Ctrl + C to copy and Ctrl + V to paste it in our document. Use Free Transform (Ctrl + T) to resize and place the worm like shown below (just over the hole).
Add a layer mask to the worm layer by choosing Layer > Layer Mask > Reveal All. Select a round soft brush and paint with black in the layer mask the upper part of the worm to give the illusion that the worm is crawling into the hole.
Let's create some shadow below our worm. Create a new layer (Ctrl + Shift +Alt + N) and place it just below the worm layer. Choose a round soft brush and paint carefully with black to create a shadow. Change the layer blend mode to Multiply and lower the opacity to around 80%.
For even a further dose of realism I decided to also add a worm reflection on our metal apple. To do this simple click on the worm layer and press Ctrl + J to make a duplicate. Put this layer below the shadow layer and lower its Opacity to 64%. Press V to select the Move tool and drag the worm a little bit to the left. It is barely visible but it's important for the realism of the whole scene.
It's time for the final adjustments. Let's take a look at what we accomplished so far. The composition looks good; however I find the image a bit too reddish for my taste. We will correct that in the next step.
Add a Color Balance Adjustment layer and decrease the red amount while increasing the blue.
Take a look at the shadow below the metallic apple. Notice that it has the a dark red hue. That's natural because it was the shadow of a red apple. But now it is the shadow of a metallic apple and it should have more cool color. In order to adjust that add a Color Balance Adjustment layer and drag the Cyan-Red slider to the left (-34). Fill the layer mask with black (you should know how to do that by now) and with a round soft brush paint with white over the shadow area (paint in the layer mask). Now we should a have a proper shadow below the metallic apple.