A startup called Gigablue claims to have reached a milestone by selling 200,000 carbon credits for its ocean-based carbon capture technology. The company says its patented particles grow algae that trap carbon dioxide, which then sinks to the ocean floor. Outside scientists, however, question the effectiveness and environmental impact of this method, citing a lack of public data and concerns about marine ecosystems. Gigablue has conducted trials in New Zealand and plans to expand operations. While some buyers trust the company's promises, experts remain skeptical about its unproven technology and the broader implications of such ocean-based carbon removal efforts.