There are two glass encapsulated RFID tags pictured above. One is intended for human flesh, the other for the scruff of your pet's neck. Which is which?
Answer: The chip pictured at the top is VeriChip's VeriMed chip that former U.S. Secretary of Health and Human Services Tommy Thompson would like to see implanted in all Americans. Directly below the human chip is the animal chip marketed by Schering-Plough under the "Home Again" brand name.
Note: The VeriChip corporation tries to ease consumer fears by referring to the chip as being "about the size of a grain of rice." The rice in the photo above is long-grain rice. As you can see, the VeriChip is much larger.
VeriChip Patient Registration Form - fine print on back
Note that the VeriChip "Instructions for Use" contains a special section for patients undergoing an MRI. Why?
University of Minnesota researcher James Lamberg has tested the VeriChip in a 1.5 Tesla MRI machine and documented his findings in a paper posted at RFID Journal here: http://www.rfidjournal.com/whitepapers/7 (subscription required) and cached here. He found "that the [VeriChip] may be inactivated as a result of MR testing."
Might not be able to read the chip in an ambulance? Yikes! Better wear a Medic Alert bracelet.