Fossils are familiar to most of us as the hardened, three-dimensional remains of ancient plants and animals, whose tissues have been impregnated by, or replaced with, minerals such as calcite, iron, and silica, thus arresting their inevitable decay. Because the mineralization process results in a rock that’s usually harder than the material around it, especially in the case of petrification, fossils are durable snapshots of the past.

But the universe of fossils also includes the impressions of such organisms, like the outline of a leaf preserved on a layer of slate, or the footprint of an animal left in mud that then filled in with sandy sediment, thus capturing this trace of the animal’s fleeting time on earth.

Collectors of fossils have an extraordinary number of pieces to choose from. Invertebrate fossils range from sponges and corals to trilobites and ammonites, the later of which were wiped out some 66 million years ago when an asteroid about six miles wide and traveling 45,000 miles per hour plowed into what is now the Yucatan peninsula, vaporizing pretty much everything on the surface of North America in about two minutes and causing the extinction of about 75 percent of the rest of the planet’s life forms in the years that followed.

Vertebrate fossils include fish, whether it’s the delicate outline of a perch or a single menacing shark’s tooth, as well as the bones of birds, reptiles, amphibians, mammals, and, yes, dinosaurs, which joined the ammonites in the planet’s last great die-off, prior to the one we’re in right now.

Trace fossils are particularly interesting. In addition to prints, trace fossils includes borings and burrows. Chondrite fossils are often mistaken for plant fossils because they resemble the branching stems of a conifer or perhaps delicate roots. In fact, they are the remains of burrows created by roundworms. Another group of invertebrates that resemble plants are graptolites, which can look like leaves (retiolites) and fanlike ferns (rhabdinopora).

Crustacea are favorites because of their familiar shapes (crabs, shrimp), as are bivalves, mollusks, and insects—for some people, the shape of a fossilized dragonfly is not only visually appealing, but also seems a link between ancient and modern times.

Still, bones are the prize, especially those of diapsid reptiles such as the megalania, which lived in Australia during the Pleistocene epoch and was the larger (20-foot-long) forebear of the Komodo Dragon. More common are the teeth and other remains of equus, the ancient cousin to the contemporary horse.

Best of the Web (“Hall of Fame”)

National Carousel Association

National Carousel Association

Since 1973, the National Carousel Association has been dedicated to preserving and restoring carousels and carousel… [read review or visit site]

Most watched eBay auctions    

Heavy Natural White Favia Brain Coral Speciman Fossil Weighing Five Pounds YqzKiller Pyritized Triarthrus Trilobite Ventral! Perfect Curled Antenna! Legs!Huge 4 5/8" Megalodon Shark Tooth Teeth Extinct Jaw Fossil Megladon Sharp Rare Nephrolenellus Trilobite! Cambrian Nevada!A-11- Premium Quality 3.62'' Large Red Colored Rooted Spinosaurus Dinosaur ToothRare! Skull Of A Pleistocene Horse, FossilGiant 5 1/8" Megalodon Shark Tooth Teeth Jaw Fossil W/display. Megladon Sharp Bone Valley Megalodon Shark Tooth 2.89"Oviraptor Raptor Velociraptor Dinosaur Egg Fossil Theropod Jurassic World Rd1Fossil Trilobites - Eldredgeops/pseudodechenella From New York5 Rare Isotelus Sp. Trilobites Ordovician Ontario Crinoid Age Prone & Enrolled Great Leg Woolly Mammoth 4.9 Kg! Fossils Pleistocene Fossil Real From Siberia!Very Large, Polished Arizona Petrified Wood Round With Tiny Crystal PocketsAsaphus Kowalewskii Trilobite Russian Long Eyes 20 MmRare Detailed Pleurocystites Squamosus Cystoid Ordovician Trilobite Age GemX-geant 1kg2 Lot 4 Nautilus Fossil Max 93mm Ammonite Nautile De Madagascar C400Lot 23 Trilobites, Various Species And SizesMuseum Quality Pyritized Ostracod Fossil! Antennae And Eggs Preserved!Fossil Trilobite - Xiangxiia / Asaphopsoides From ChinaRare Acernaspis Trilobite W Lichid Segment! Silurian Quebec!Fossil Brittle Stars - Stenaster Salteri From Ontario, CanadaAsaphus Robustus Trilobite Russia Very Nice Great Leg Woolly Mammoth 11 Kg! Fossils Pleistocene, Fossil Real From Siberia!Fossil Eurypterid - Eurypterus Remipes From New YorkLot 15 Trilobites, Various Species And SizesRare Detailed Crinoid Cupulocrinus Jewetti Ordovician Ontario Trilobite Age Gem Czech Fossil Trilobite Onnia Superba Ordovician Positive + NegativeRare Ice Age Bison Horn Florida Fossil ~57~Fossil Eocrinoids - Gogia Sp. From UtahJenkinsonia Trilobite! Cambrian Utah!C276 106mm Copal Amber Insect Inclusion Fossil Ambre Hant Fly Mosquito SpeederRare Complete Kimbarella Quadrata With Fine Detail: White Sea, RussiaSpectacular World Class 325 Million Year Old Fossil PentremitesOosik Baculum Fossilized Walrus Alaska Agatized 16"Geant 554g 138mm 5.5" Fossil Ammonite Zebra Stone Madagascar C578 NautilusEurypterid Fossil - Eurypterus Remipes Sea Scorpion Rib Of The Woolly Mammoth Fossil Fossils From Siberia!Fossil Cystoid - Caryocrinites Ornatus From New YorkX-geant 1kg4 Lot 4 Nautilus Fossil Max 100mm Ammonite Nautile De Madagascar C404Fossil Eocrinoid - Gogia Sp. From Utah #2Fossil Edrioasteroid - Cryptogoleus Chapmani From Ontario, CanadaXl Lot 5 Fossils Ammonite Nautilus Nautile Stone Madagascar Shell D971 CrystalX-geant 1kg4 Lot 2 Nautilus Fossil Max 136mm Ammonite Nautile De Madagascar C402Big Nautilus Fossil Pierre Stone Ammonite Paleontologie D997 64mm 144gFossil Crinoid - Zeacrinites Wortheni From AlabamaEurypterid Remipes, Sea Scorpion FossilX-big 243g 81mm Fossil Clam Shell Coquillage Pierre Collection Madagascar C313Big 223g 100mm Fossil Ammonite Zebra Stone Madagascar M200 Nautilus FossileGiant Fossil Sand Dollar / Echinoid Dendraster VenturaensisRare Big 72mm 158g Alectryonia Fossil Huître Oyster Bivalve Ostreidae D841Most Bigger 381g 112mm Oursin Sand Dollar Fossil Echinoid Madagascar Urchin C508A131-natural Association Of 2 Ordovician Fossil Brittlestar (ophiura Sp) MoroccoPsittacosaurus • Replica Psittacosaur Skeleton • Life Size Dinosaur Fossil CastDinosaur Egg Nest Dendrolithus Hadrosaur Duckbill Fossil Jurassic Cretaceous G4q14" Triceratops Skull Frill Fossil Rib Bone South Dakota Badlands Dinosaur Fossil Hell Creek Tyrannosaurus Rex ToothHalf Mammoth Jaw 6.1 Kg!!! Fossils Pleistocene Mammoth Siberia In Russia!Fossil Trilobite - Isotelus "mafritzae" From Ontario, CanadaLarge 5 1/2 Inch Megalodon Fossil Shark Tooth - South CarolinaManchurochelys Liaoxiensis Turtle Fossil Skeleton With Skull Claws Cretaceous