Fizzy Marbles

You have to be quite old to remember these being in circulation. Ok, you'd likely be dead, because I think they went out of production about a hundred years ago. 

The marble was held with a rubber washer against the neck of the bottle, which held the carbon dioxide in and retained the fizz in the fizzy lemonade. You had to knock the marble down into the bottle to get to the drink, releasing the fizz. 

Often, after the drink was consumed, children would smash the bottles to get to the marbles. These two, however, appear to have escaped. On the whole and despite the smashing, a more environmentally friendly drinks bottle than the casually tossed aside plastic ones...