Discovery Most trilobite fossils are over a million years old, so they have been commonly found and used as toys and decorative pieces by humans for thousands of years. However, the first proper scientific description was made only in 1689, by Wan Shizen of China. The first scientific diagram of a trilobite then came in 1698, by Rev. Edward Lhwyd in a book called 'The Philosophical Transactions of the Royal Society'. In the book, the trilobite was mistakenly called a flatfish. Over time, with an increase of interest in paleontology, fossils of around 20,000 species were documented. Trilobite Evolution Timeline While most fossils consist of just the hard exoskeleton, in rare cases, even the softer body parts, including the legs, gills, antennas, etc., have been found. Fossil records indicate that the first trilobites were soft-bodied creatures that slowly evolved shells as they transitioned from the Precambrian to the Cambrian Period. The Cambrian Period saw them multiply rapidly and dominate the seas of the Paleozoic era, diversifying into innumerable species as they evolved further―their body adapting to the environment of shallow reefs to abyssal depths of the ocean. The Ordovician, Devonian, and the Great Permian extinction events, eventually took their toll on these wondrous creatures, making them extinct. Fortunately for us, their exoskeletons survived as fossils, and we are able to enjoy and learn about the Earth that existed millions of years ago. How a Trilobite Fossil Forms A trilobite fossil is normally formed only if certain conditions are fulfilled. This includes sudden and permanent entombment of the creatures, with continuous addition of sediment without significant erosion, and a lack of oxygen, heat, and compression, which severely limits the decay. Due to the fact that trilobites existed across all the seas of the world, and also because fossils have a higher chance of forming underwater, millions of trilobite fossils are available today. Trilobite fossils are some of the most well-preserved and beautiful collectibles in the world, and are sought by enthusiasts all over the world due to the fossil's unusual and interesting appearance. The innumerable species make a vast variety in their shape and color. Due to their abundance, paleontology enthusiasts can get them for affordable prices. So, keep your eyes peeled the next time you are on an excursion in the wild, you might just find yourself a beautiful piece of history.