Continental crustal fragments, partially synonymous with microcontinents, are fragments of continents that have been broken off from main continental masses forming distinct islands, often several hundred kilometers from their place of origin. All continents are fragments; the terms "continental fragment" and "microcontinent" are restricted to those smaller than Australia. Other than perhaps Zealandia, they are not known to contain a craton or fragment of a craton. Continental fragments include some seamounts and underwater plateaus.