One Cell, Many Rooms

What look like grapes or bubbles are actually chambers of a single-celled foraminiferan (or foram). Almost 1mm in diameter, the foram is large enough to see with the naked eye. It was living inside a stromatolite, a rocky structure made of sediment grains held together by compounds made by cyanobacteria and other microbes. Once abundant along ocean shorelines worldwide, stromatolites nearly disappeared about one billion years ago. WHOI scientist Joan Bernhard and colleagues recently showed that foraminifera may have contributed to their decline. This foram from Highborne Cay, Bahamas, has been fluorescently labeled with CellTracker Green™. (Photomicrograph by Joan Bernhard, Woods Hole Oceanographic Institution)