Tool use was once considered one of the defining traits of human intelligence. Then we discovered chimpanzees using sticks, crows fashioning hooks, and sea otters cracking shells with rocks. Now add dolphins to that list. Wild bottlenose dolphins in Australia have been documented using sea sponges as tools to protect their snouts while hunting on the seafloor, and a 2025 study revealed just how cognitively demanding that behavior actually is. Here is the full story of what dolphins are doing out there, and what it means for how we understand ocean intelligence.