There are a number of synonyms for the term "oceanic crust" that are frequently used in geology and earth science. One common alternative is "seafloor crust," which refers to the bottom layer of the ocean that covers the seafloor. Another term used to describe this area of the Earth's crust is "basaltic crust," which reflects the fact that the most prevalent type of rock here is basalt. Other synonyms may include "marine crust," "ocean bottom crust," or simply "ocean crust." Regardless of the terminology used, however, all of these terms refer to the thin layer of rock that covers the ocean floor and plays a critical role in shaping the planet's geography and biosphere.