Locked chest

Locked Chests (also known as Steve Co. Supply Crates) have been added with Minecraft Beta 1.4. They generate naturally on the map. Clicking on the chest will bring you in the screen shown on the bottom. Clicking on "Go to Store" will forward you to the Minecraft Store. The chests emit light at level 15 and are indestructible by hand or with a tool, but can be removed by explosions (which may drop them as an item, allowing them to be placed elsewhere). They are an April Fools' Day joke. Notch is planning to remove these at midnight tonight. Although there's a chance he wont due to illness.

Trivia

 * Locked chests are a reference to the Mann Co. Supply Crates from Team Fortress 2, where a key must be purchased for $2.49 in the in-game shop called Mann Co. Store in order to open the crate.
 * When you go on the Minecraft store website and click proceed to checkout, a screamer occurs when a dinosaur jumps out of the bottom of the page, making a growling noise and flying off the screen showing that this is indeed an April Fool's Joke.
 * Entering items totalling over 10,000 Dollars into the cart causes a window popup asking if you are prone to seizures. Entering OK makes the screen start flashing. When first released there was no seizure warning label, Notch later implemented it to avoid lawsuits and posts on the forum.
 * This may have been what Notch was talking about in his Twitter post about a "silly secret project".
 * Locked chests can even generate in mid air.
 * It is more cost efficient to buy five Steve co. supply crate keys than it is to buy a five pack.