Physarum

Slime molds are peculiar protists that normally take the form of amoebae, but under certain conditions develop fruiting bodies that release spores, superficially similar to the sporangia of fungi. They should not be confused with true moulds, which are actually fungi. Although cosmopolitan in distribution, they are usually small and rarely noticed. There are several different groups.
Most notable are the plasmodial slime moulds or myxogastrids (also known as acellular or true slime moulds), where the feeding stage takes the form of a giant amoeba with thousands of nuclei, called a plasmodium. It is not divided by cell membranes, but rather is enclosed by a single outer one, and is thus like a single large cell. Most are smaller than a few centimeters, but the very largest reach areas of up to two square meters, making them the largest undivided cells known. Many have bright colors such as yellow, brown, and white. Under dry conditions they may form resting structures called sclerotia. Once produced, spores release biflagellate or amoeboid gametes, which fuse pairwise to produce new plasmodia.

Amazing News
In 2006, researchers at the University of Southampton and the University of Kobe reported that they had built a six-legged robot whose movement was remotely controlled by a Physarum slime mold. The mold directed the robot into a dark corner most similar to its natural habitat.