A Duanda was between 30 to 35 feet tall with thick purple fur and three-foot-long claws. It was strong enough to pick up a human with one hand.
In 2266, Spock was captured by a terrorist on Fayo who gave Kirk three minutes to trade Spock's life for that of Prince Yano, son of Emperor Bavoda. A Starfleet oath prevented Kirk from negotiating with the terrorist. As he weighed his actions, Kirk thought back to memories of his friend, including incidents with the Duanda, the Brain Ray Robot and Asteroid Delta. (TOS comic: "Prince Traitor")