In 2266, Crucial III was surveyed by the USS Enterprise. A seven-member landing party led by Hurst explored the lush surface while Spock correlated data. When Spock realized that the planet was about to explode, Hurst and his team hastily fled the surface in their space bug, and the starship narrowly avoided explosive shock waves.
Unfortunately, contaminating pollen from the planet infected the brains of the landing party, driving the seven people temporarily into a state of near madness before Spock could develop an antigen. (TOS comic: "The Crucial Element")