A device and method for the sea-based culture of sea urchins and abalones, such device which is composed of two lateral elements which are parallel to each other in the longitudinal direction, where each one of their ends has a groove and a hole for the installation of at least 4 braces, two above and two below, such braces which permit joining the lateral elements, leaving a separation between them, they form in their exterior perimeter the external contours of the lateral elements, while the center areas of the braces have, on their interior surface, a plurality of parallel and
equidistant guides, for the installation of a plurality of plates which are vertically inserted into the guides, forming spaces between the plates that permit housing sea urchins or abalones on both faces of such plates, in which each plate has a
flange at its top and two holes at its base, such holes through which a pin is inserted to attach the plates to the bottom braces; while at the bottom of the device, below the plurality of plates, a horizontal tray is provided to hold
algae for feeding the sea urchins and the abalones; wherein, both the plurality of plates and the tray are enclosed in an elongated mesh having the width of the separation of the lateral elements, wherein the ends of the mesh are joined to the ends of the lateral walls of the tray, in such a way that the length of the mesh wraps around the plurality of plates in the longitudinal direction of the lateral elements.