It's the remains of a "whip-it" or "whipped cream charger" which is just a tiny little canister of N02. It's supposed to be used as a little recharge of pressurized gas for something like this so that you can make your own whipped cream, but because the canisters contain laughing gas they get abused.
It's probably too late for this advice but a bar in Austin called Craftsman keeps their egg whites in a whip its canister so they don't have to spend time dry shaking them. They keep them chilled in the fridge next to their vermouths. They'll also have several canisters infused with things like Velvet Falernum or Green Charteuese to save even more time.
http://www.amazon.com/Whip-It-Professional-2-Liter-Anodized-Dispenser/dp/B000E8VM46
So they'll dispense the egg whites into the cocktail glass like whipped cream filling it half way. Then they shake the rest of the ingredients, then strain it over the egg whites and somehow it just ends up perfect without stirring.
it was a foam... like used in other kitchen applications to make whip cream ect. like this. http://www.amazon.com/Whip-It-Professional-2-Liter-Anodized-Dispenser/dp/B000E8VM46
he put this into the miso broth. with a smashed suevied egg.
Yeah, I mean exactly that.http://www.amazon.com/Whip--Professional-2-Liter-Anodized-Dispenser/dp/B000E8VM46/ref=sr_1_3?ie=UTF8&qid=1327083138&sr=8-3
I think the crackers are supposed to be used to release canisters that aren't going to be used before disposal or something like that. http://n2ocrackers.com/