Strange matter is a substance made of a slurry of up, down, and strange quarks in about equal numbers.
There are two types of strange matter, depending on how it was created, and each has different times of decaying into normal matter.
Stable strange matter
This type of strange matter is so overwhelmingly stable that it can convert normal matter into strange matter when it comes in contact with it. Because of its extremely high stability, it will decay into normal matter in a time longer than the expected lifespan of the universe.
It originates by compressing quark matter in extremely high pressures, and are located in the core of some neutron stars, but they can leave their interior in the form of strangelets. These strangelets, which can be as small as a drop, can turn an entire planet like Jophtio and its moons into strange matters within seconds.
Stable strange matter can also be produced in specially designed particle accelerators.
Due to the alarmingly fast speed it can convert other types of matter into strange matter, it is widely considered an extremely dangerous substance, making it illegal to harvest and synthesize, although most organizations like the Corporation Fujibayashi Antimatter and terrorist groups prefer to try to artificially produce it over-harvesting it, as it is less expensive.
Fujibayashi Antimatter owns 99.9% of this artificial strange matter and sells it exclusively to The Supreme.
Unstable strange matter
Although it has never been found, traces of a new type of strange matter that can quickly decay back into normal matter have been found on Karine Planet.
It has been theorized that this type of strange matter is created by compressing the space-time continuum to an extreme that normal matter could become strange matter. Because of the extreme time stretch, the time for this particular type of strange matter to decay to other types of matter would end up being in about 5 seconds.
However, it retains the capability of converting normal matter into unstable strange matter, acting like an extremely powerful acid. Although it has never been able to be artificially created, the Deep Nebula Federation banned any intent of harvesting and synthesizing it.
Strange matter is very useful in its unstable form. Strange matter can be used to generate power extremely efficiently. Its energy density is greater than antimatter. However, this mode of energy production is very difficult to pull off and is only used very rarely, due to the bad cost-benefit (it is too expensive).
The stable strange matter has very destructive properties, because of this it can be used to destroy anything. Planets, ships, or superstructures could be destroyed in seconds. The stable strange matter was used extensively as a weapon by The Supreme and DELYATU during The War for All. There were even occurrences during TWE where it is told that The CoB and The Commonwealth attempted to use Strange Matter against The Seekers.
While not tested, unstable strange matter theoretically doesn't have as much caliber as stable strange matter, so it didn't get much attention as a war weapon.
Stable strange matter is very difficult to contain. To contain it, it must be stored in a bubble of warped space-time. This takes a lot of energy to contain, for every gram of strange matter it takes 1.7*10^40 watts of power to store per year. Normally unused strange matter is sent into black holes for disposal.