In other words, science has shown how unicellular organisms like the slime mould have the ability to learn and remember. Memory and learning seem to not be limited to us humans and can be found, as expected from an evolutionary perspective across organisms.

The amoeba Physarum polycephalum is quite a performer as it has been able to navigate mazes and solve simple puzzles.
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Nakagaki, T., Yamada, H. & A. Tóth. “Intelligence: Maze-solving by an amoeboid organism” Nature 407, 470 (2000).

The plasmodium of the slime mould Physarum polycephalum is a large amoeba-like cell consisting of a dendritic network of tube-like structures (pseudopodia). It changes its shape as it crawls over a plain agar gel and, if food is placed at two different points, it will put out pseudopodia that connect the two food sources. Here we show that this simple organism has the ability to find the minimum-length solution between two points in a labyrinth.

Members of this class are commonly referred to as slime moulds. These have thought to belong to both animal and fungi kingdoms at one time or another. It’s now known that they are quite unrelated to animals and fungi and now are classified in the Kingdom Protista.

However slime moulds do exhibit characteristics of both fungi and animals. In the feeding stage, the slime moulds moves about as a mass of protoplasm (the plasmodium) feeding on bacteria, spores, and other organic matter much like an amoeba. When the food supply is exhausted or other unfavourable conditions occur, the plasmodium changes, taking on the appearance of a fungus.