Stasis Egg

From LSWiki

Extremely rare items (one every few days) that give you a random thing upon opening. They're lootboxes. I remember you had to solve a little puzzle of the type 5 + 7 = ? to open them, but I may be wrong.

Circa ~2016 there was a lux option to purchase them, at 5 each. Quality or usefulness of the item were not guaranteed. At some point later, the option was removed.

They were present for a moderate period of time at Hank's shop, but they also were removed from there.