Yes it is part of the Adams penny to dime trick! It is called a shell
you show the loaded shell and block and then place on the back of somebodies hand.
on the hand.
Dime and steel disk in shell
Shell held in place on block by magnet
Shell, block and the two items you have to supply, a dime and a regular penny the backs are shown on the pennies due to the fact they are all the same or were. No dates.
after picking up the shell you scrape and palm the shell off the block, so you can show the bottom. Cheap sold for a couple dollars in years past. Now under $5.00 http://www.magictricks.com/adams-magical-block.html
Here is the vid from adams it is better when done like I described.