Toad is a period-2oscillator that was found by Simon Norton in May 1970.[1] It is one of very few known oscillators that is a polyomino in one of its phases. Toads often appear in large, complex patterns because of their ability to eat things when paired together (as in killer toads). Additionally, toads are useful as building blocks for constructing large oscillators with periods that are a multiple of two because of the various ways in which they can be hassled.
A toad flipper is a hassler that works by having two dominosparkers (pentadecathlons in the example shown below) apply their sparks to the toad in order to flip it over.[4] When the sparks are applied again, the toad is flipped back. Either or both domino sparkers can be moved down two cells from the position shown and the toad flipper will still work, but because of symmetry there are really only two different types of toad flippers. For another example of a toad flipper, see 186P24 and the period 4 turning toadswick.
A toad sucker is a toad hassler that works by having two domino sparkers (pentadecathlons in the example shown below) apply their sparks to the toad in order to shift it.[5] When the sparks are applied again, the toad is shifted back. Either or both domino sparkers can be moved down two cells from the position shown and the toad sucker will still work, but because of symmetry there are really only three different types of toad suckers. A p4 example is shown in the "subsequent improvement of the p44 gun" as a sparker in the p44 pi-heptomino hassler article.
Additionally, moving toad suckers have been created that use the domino sparks from two parallel even-period spaceships to escort a toad.
It is also possible to simultaneously shift and flip a toad using one domino spark. However, the domino spark must be inserted in a special way that would not result in a domino spark without the toad. Two spaceships that are suitable sparkers, one on each side, can escort a toad similarly to the moving toad suckers mentioned earlier except that the amalgamation moves two squares orthogonal per period instead of one square orthogonal per period.[6]
