shapetst is an unused area located in the Pikmin game files. Its name most likely means that it was used for testing shapes in the game's development.
Gameplay Footage
shapetst starts at about 4:43 in this video: {{#ev:youtube|kl0pagZp6r4}}
Geography
The S.S. Dolphin and Onions land in a circular water pool area; although it apparently isn't deep enough to cause Pikmin to drown. In the middle of the area there are large hill-like structures that add to the evidence of the map being orginally used for testing shapes. There are also many lily pad-like platforms in the water. Many textures are unused, and the map has many openings where Captain Olimar can easily fall off into an endless abyss. Outside of the circular area where Olimar landed in, there is a path that leads to another part of the map where there are many tin cans and what appears to be the word "YAKU" on the ground. There are also what appear to be bottles of some sort that are transparent and have no collision at all. Instead of an actual background, there is a large wall that envelopes much of the starting area that has a generic forst texture on it.