Koro was a sentient octopus. He was a Federation ambassador who resolved the Great Soolian Algae Crisis of 2341 by communicating with the algaeic slime mind at the Starfleet Aquatic Research Center. Protecting Koro figured prominently in Brad Boimler's 2381 holonovel Crisis Point II: Paradoxus.
In the story, a trio of Romulans used the Chronogami to travel to the year 2341 to interfere with Koro. After being foiled by the protagonists, they would travel further back in time to 1982, in an attempt to destroy Koro's ancestor, who was housed at an aquarium in Sydney, Australia on Earth. (LD: "Crisis Point 2: Paradoxus")
It is unclear whether Koro was a real historical figure or a fictional creation.