Dolphins may be communicating with each other about seaweed. No, really.

Scientist Denise Herzing was swimming with a dolphin pod in the Caribbean last August when she heard one say, “sargassum,” according to New Scientist. Actually, the dolphin didn’t actually say ‘sargassum.’  It whistled a specific whistle that she and her team used to stand for the seaweed when playing with the pod in the hopes they would adopt the whistle and use it.

“It was like whoa! We have a match. I was stunned,” Herzing said in New Scientist. She was wearing a dolphin translator device called the ‘Cetacean Hearing and Telemetry,’ or CHAT, that said the word ‘sargassum’ in her own voice when it picked up the particular whistle being used by the dolphins.

The CHAT translator was developed for Herzog by Thad Starner — who also helped create Google Glass — and a team of graduate students at Georgia Institute of Technology, according to the Daily Mail. Herzing, who is the director and founder of the Wild Dolphin Project, has been studying a particular dolphin pod for 25 years and uses the device while listening to the dolphins interact.

The device has a keyboard with four symbols that correspond to specific sounds, as reported in the Daily Mail. The diver wears it on an arm and can play specific tones for an object through a speaker while interacting with dolphins. It picks ups up the natural tones they make through two hydrophones and this was the first time that it matched a tone with a word and translated it. It wasn’t clear if the dolphin said ‘sargassum’ when seeing some or if it was talking to another dolphin.

Herzing and her team also invented tones to match ‘scarf’ and ‘rope’ for items they gave the dolphins to play with, according to Discovery News.

“The dolphins had been playing with sargassum and with each other,” Herzing told Discovery News. “However, it should be made clear that the mimic of a sound does not mean that the function of that sound is understood. That comes over time with exposure to how a word is used, and this is a challenge in the wild.”

CHAT continues to improve, though, and with it comes a heightened chance of holding conversations with dolphins, or at least understanding them better. “Sargassum” might be one small whistle for dolphins, and one giant leap for interspecies communication.

But so far, this has been the only dolphin use of the ‘word.’