The Greech (known to the Borg as Species 433) were a sentient, non-humanoid cytoplasmic species living in the Delta Quadrant. The Greech were native to a binary star system 100 light-years from the Indign system, on the border of the Beta Quadrant, 30,000 ly from Earth. (VOY novel: Unworthy)
Compared to the cytoplasmic pseudo-parasite, the Greech were significantly smaller. Like their cousins, the Greech communicated with shrieks, giving their name an onomatopoetic quality. Starfleet's universal translator was unable to parse their language.
Their body was segmented. Their tails became smaller towards the end point. Two antennae sprang from the head. A Greech had a pair of large orange eyes.
The Greech were able to enter a symbiotic relationship with other species. The Indign cooperative contained Greech. These Greech secreted a substance that nourished the humanoid Neyser. Because the Greech were a non-telepathic species, communication was facilitated by the Imalak. Within a cooperative, which was formed and dissolved of individual volition, a Greech was wrapped around a Neyser's arm. (VOY novel: Unworthy)
Thousands of years ago, the Greech settled the third planet in the Indign system. When the Neyser crashed on the planet, a bloody conflict erupted, which was diminished when the Neyser modified the Imalak and Neela to facilitate communication. The Imalak were able to understand the Greech, and the Neyser modified the Neela to translate. The Neyser soon discovered the healing properties of the Greech. Fascinated by the collective, the Irsk and Dulaph asked to join and were modified to do so. The collective lived in peace for a hundred generations since then.
In April 2381, first contact occurred between the Federation and the Indign collective when the Project Full Circle fleet investigated the system for Borg activity. The Indign cooperatives ignored the Starfleet explorers at first but opened up to them later on, even visiting USS Voyager. Fleet Commander Willem Batiste refrained from informing the Indign collective about the Federation's involvement in the ending of the Borg Collective at the hands of the Caeliar. (VOY novel: Unworthy)