The Square-0 (a.k.a. SQ0) is a cube-shaped twisty puzzle. It is a lower-order version of the famous shape-shifting puzzle Square-1. It was invented in 2015 by YouTuber DGCubes (Daniel Goodman) for a school project where students were given the task to invent something and then present it to the class in Spanish. To make the prototype, Goodman bought a Square-1 puzzle and simply "bandaged" each corner piece with an adjacent edge piece. We say "simply" because turning a Square-1 into a Square-0 is not hard to do, but we do think the original idea is GENIUS! Apparently we're also not alone on that since ShengShou decided to mass-produce the puzzle and nowadays you can buy it directly under the name "SengSo SQ0".
It might not be very obvious at first glance, but the Square-0 can actually be thought of as a bandaged Tower Cube (2x2x3) shape-mod. The top and bottom faces each have 4 identical corner pieces, and the puzzle itself is made of 3 layers. The only difference between the mechanism of the Square-0 and the one found in the Tower Cube (2x2x3) is that the former only has two parts in its middle layer. This makes the Square-0 even easier to solve than the Tower Cube (2x2x3), which is already considered an easy puzzle to solve. Our computer simulation shows that the Square-0 only has around 80k possible combinations.
The Square-0 is not an official WCA puzzle. Its predecessor, the Square-1, is the only shape-shifting official WCA puzzle. At the time of writing, we couldn't find any unofficial record for the fastest solve of this puzzle.