s of chemo attractants and repellents [@durham1976control; @ueda1976chemotaxis; @rakoczy2015application]; it responds to chemical or physical stimulation by changing patterns of electrical potential oscillations [@ridgway1976oscillations; @kishimoto1958rhythmicity] and protoplasmic tubes contractions [@wohlfarth1979oscillatory; @teplov1991continuum];

-   it optimises its body to maximise its protoplasm streaming [@dietrich2015explaining]; and,

-   it is made of hundreds, if not thousands, of biochemical oscillators [@kauffman1975mitotic] with varied modes of coupling [@grebecki1978plasmodium].

Here we offer very short descriptions of actual working prototypes of Physarum based sensors, computers, actuators and controllers. Details can be found in pioneer book on Physarum machines [@adamatzky2010physarum] and the ‘bible’ of slime mould computing [@adamatzkyAdvancesPhysarum].

Optimisation and graphs
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Shortest path and maze {#path}
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Given a maze we want to find a shortest path between the central chamber and an exit. This was the first ever problem solved by Physarum. There are two Physarum processors which solve the maze. First prototype [@nakagaki2001path] works as follows. The slime mould is inoculated everywhere in a maze. The Physarym develops a network of protoplasmic tubes spanning all channels of the maze. This network represents all possible solutions. Then oat flakes are placed in a source and a destination site. Tube lying along the shortest (or near shortest) path between two sources of nutrients develop increased flow of cytoplasm. This tube becomes thicker. Tubes branching to sites without nutrients become smaller due to lack of cytoplasm flow. They eventually collapse. The sickest tube represents the shortest path between the sources of nutrients. The selection of the shortest protoplasmic tube is implemented via interaction of propagating bio-chemical, electric potential and contractile waves in the plasmodium’s body, see mathematical 