Spikes

Make a new file in photoshop around 900 x 900 px .

Fill it with black colour.

Next make a new layer above the background.  Select the circular marquee tool and make a selection .

Choose the gradient tool and select radial gradient. choose the spectrum gradient.

Apply the gradient to the circular selection.

Deselect it and then merge the layer into the background.

Go to filter menu an select filter>stylize>extrude
 reduce the size to something less than 20........ the lesser the size of the pixels the thinner the spikes.

 Now run the same filter ( Ctrl+F) a few times more.

Make another layer on top of it and change the blending mode to colour. then fill it with whatever colour u like.

That's it......... u got 3D Spikes...