Did you know that until the 16th century, mariners and seamen referred to sharks as "sea dogs"? Sharks have actually been around for a long time--many scientists think a variation of the shark existed from over 420 million years ago! Sharks belong to a large group of fish that have a skeleton made of cartilage instead of bone. Because of this, the only fossilized remains of ancient sharks are their teeth.The teeth of sharks grow in constantly to replace older ones that wear out. It is estimated that sharks can lose up to 20,000 teeth in their lifetime. In fact, some ancient sharks had teeth that grew as long as 4 inches.
Want a great example of a shark tooth fossil? Invest in this inexpensive, authentic shark tooth fossil specimen to spruce up your science classroom! Also makes a unique gift, stocking stuffer, or party favor for adults and children alike!
With this kit, you can conduct 25 experiments to learn how an electric motor converts electricity into motion, and how an electric generator does just the opposite, converting motion into electricity.
Ever wonder how to survive in the wilderness? These cards can help!
Great reference card for chemistry and physics students.
This SUPER Erector Construction set is one of the best you'll find anywhere!
This genuine meteorite is great for the rock collector in your family!
Shake the Pet Tornado clockwise and watch the mini tornado funnel form before your eyes!