A CTD unit (conductivity, temperature and depth recorder) is lowered from a research ship using a hydrowire. The unit records these parameters as it is lowered into the ocean's depths. This recording unit is surrounded by a circle of Niskin bottles. These bottles have lids on both ends. They are designed to electronically open and close when they reach the depth at which water samples are required. All of these units are collectively referred to as a "CTD rosette" and are a regularly used piece of equipment by marine biologists and oceanographers. This image was taken in 2007 courtesy of the Monterey Bay Aquarium Research Institute.