The Annuated, also known as The eldest of the Interior People and Their Progenitors are ancient Trill symbionts whose age ranges above 20,000 years old, living in the deepest part of the Caves of Mak'ala.
The Annuated look similar in shape to their younger descendants, but are approximately 30 meters long and 8 meters in circumference. They also spout a number of tentacular projections along their lengths which emit bioplasmic discharges. They are bottom feeders who subsist on nutrient rich hot springs at the base of the Mak'ala cave network.
The Annuated spawn eggs that eventually develop into the younger Symbionts which are released into the "shallows" of the Mak'ala caves, where they are tended by the Guardians. They also collect the memories of younger Trill Symbionts who return to the caves to die.
The Annuated Symbionts are serviced by smaller caretaker symbionts, who care for the Annuated as well as push the newly spawned eggs into the shallows. These caretakers are only between 2 and 5 thousand years old and measure a mere 2 meters in length, but also have immature tentacles growing along their breadth. Vah and Memh were some of the many such caretakers.
Ezri Dax once encountered the Annuated, after being directed to the bottom of the Caves of Mak'ala by a number of Symbionts and their Guardians. She spoke to the Annuated, who revealed the truth about the Symbionts, Bluegill parasites and Kurl links. The first time she met one, she assumed they were responsible for the myth of the Mak'relle Dur. (DS9 novel: Trill: Unjoined)