Ben Kamens, the first hire and lead engineer of Khan Academy, the ultimate Silicon Valley education platform, founded a new startup called Spring Discovery dedicated to defeating aging and extending life. The company told Business Insider it raised $18 million on Tuesday from venture firms like First Round Capital (backers of Square and Flatiron Health) and General Catalyst (backers of Snap and e-commerce site Jet). The new funding puts the startup on the $850-million longevity map for the first time.