Step 1 : Introduction to the question "What are oyster larvae called once they attach to a surface?"
...Oysters reproduce by spawning tiny larvae. These navigate freely through the water until they come across a structure that will serve as a suitable habitat. They then settle on this structure, permanently attaching themselves to the surface. Once this occurs, they become known as spat. People cultivate oysters the world over for food and pearls. For successful oyster farming, the larvae much have suitable surfaces on which to settle within a hatchery or in a wild setting. This surface, or substrate, is usually the shells of other oysters or ceramic tiles. Once attached, oysters filter the nutrients they need directly from the water, making them self-sustaining. Source: OceanService.NOAA.gov
