Relax your eyes until you see a fourth image appear. Depending on whether  you  cross or separate your eyes, one of the two images in the middle will be the correct 3D image and the other middle image will be the opposite direction 3D.

3D Fluorescence Microscopy
Fluorescence photomicrograph of race horse bone using triple band pass filter. The colors show areas of bone formation. Mag. 75x. (Preparation courtesy of Dr. Chris Riggs, Dr. Michael Provost & Prof. Alan Boyde. Photomicrography by Dr. Gary L. Greenberg)

Race Horse Bone
Horse third metacarple, from rigorously trained animal, stained with 6 different fluorescent markers. (Dr. Michael Provost, Prof. Alan Boyde, and prepared by Dr. Christopher Riggs. Photomicrography by Dr. Gary L. Greenberg)