This year marks the 150th anniversary of one of the most important expeditions in scientific history. HMS Challenger travelled the world's oceans between 1872 and 1876, revealing that the ocean was much more complex than had been anticipated. The expedition discovered thousands of new species, and even discovered the deepest trench on Earth - the Mariana trench. Scientists from around the world are gathering at the Museum this week to mark the important discoveries the voyage made, and you can explore our image gallery to see just a few of them. Discover how science is still informed by Challenger today via our link in bio. 1) HMS Challenger was a former naval warship which was converted into a floating laboratory for the expedition. Most of its guns were removed to make way for the latest in Victorian scientific equipment, including dredges, laboratories and depth sounding apparatus. This enabled the ship's scientists investigate all aspects of the ocean - including physical, chemical and biological. 2) Challenger discovered over 4,700 new species in total. Its finds include over 10% of all known living starfish species, which play a variety of ecological roles in the ocean. 3) Aside from living species, Challenger also improved our knowledge of extinct ones. The thylacine is a Tasmanian mammal driven to extinction over 80 years ago. Specimens collected by Challenger provided some of the most detailed anatomical studies of the species. 4) This ring of shells is made up of foraminifera, a group of plankton found around the oceans of the world. Comparisons between Challenger's foraminifera and more recent samples has shown their shells are getting thinner as a result of climate change. 5) This is a polymetallic nodule - one of the first ever discovered. Challenger discovered these potato-sized lumps of metal at the bottom of the ocean, which could in future be a source of materials for renewable technology. 6) Some of Challenger's finds were out of this world. Ocean sediment from the voyage contains micrometeorites, which tell us more about the universe.