A Gregor's Mat is a terrestrial colonial mat-like organism, made of trillions of amoeba-like cells from the Orion's Arm Universe.
During the sporing season the individual amoebas that make up a Mat will combine to form a single super-organism that may reach several square kilometers in size (the largest was 6,700 km2). They will remain in this state for weeks before dispersing or attenuating. However, some Mats may last for months. Mats will, in this state, show emergent behavioral properties beyond that of individual amoebas, but they are not considered sapient or even sub-sapient.
Gregor 23 was an explorational relativistic Von Neumann probe and poet-theologian that cataloged some 504 stars and planetary systems, some of which included extremophile prokaryote ecosystems (this was the only one with a rich ecosystem). Its last known message was received in 10035 AT. Claims that succumbed to things like pirates or enemy spacecraft can be safely discarded.
The Gregor's Mat comes from a Garden World called Euripedes Mey (YTS 102483210-IV). Near M48, it was first explored by a relativistic Von Neumann Probe called Gregor 23 during the early Second Federation Period. The ecosystems on Euripedes Mey are mostly solitary and colonial protistoid. Although about 58,000 species have been recorded, there are no multicellular animals (the Gregor's Mat being the most complex). However, multicellular plants are common but of a simpler grade than Terran plants. These include dense thickets of Land Kelp, Higgirt Moss and several thousand other species which flourish in the moist valleys and lowlands. The drier uplands are devoid of anything other than microbial life.