Is there a block that falls when stepped on in Minecraft?

Is there a block that would automatically drop to the ground when the player steps on it?

I googled for a solution but didn't find one. It should be possible to accomplish something similar with redstone and pistons, but being very new to Minecraft I wonder if there is a much simpler and more elegant way.


Solution 1:

A sand block with string on top of it will act like this, but can only be placed with commands.