Two subclasses of cestodes are differentiated on the basis of the numbers of larval hooks, the Cestodaria being decacanth (10 hooks) and the Eucestoda being hexacanth (6 hooks). Collectively, 14 orders of cestodes have been identified according to differences in parasite morphology and developmental cycles.
Most meteorites originate between Mars and Jupiter, where a belt of asteroids has lingered for 4.5 billion years, since the solar system was young. No rock on Earth is as old as a meteoriteâall terrestrial material has been ground, melted, and reformed by plate tectonics. Meteorites have other, less common, origins. Meteor impacts on the moon or Mars can eject surface material into space that ends up on Earth. Last year a 10.5-ounce meteorite that originated on Mars fetched $94,000. A 4-pound lunar meteorite, the most expensive ever auctioned, sold for $330,000 in 2012.
A meteorite is a fragment of rock or iron from outer space, usually a meteoroid or asteroid, which survives passage through the atmosphere as a meteor to impact the surface of the Earth. Meteorites are believed to originate in the asteroid belt between the planets of Mars and Jupiter. A meteorite may range in size from less than a gram to more than 60 tons. When the path of these space rocks intersects with Earth's orbit, the meteoroid enters the atmosphere at high velocity causing the luminous phenomena we call a meteor or shooting star.