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The Fossilized Crab Claw (And How It Formed)

Interesting Things From Around The Internet #3: The Opal Crab Claw

This is the third post of my “Interesting Things From Around The Internet” series. If you missed the first two, I link to them at the bottom of the post.

crab claw turned into opal

Stumbling around the internet this week, I ran across this fossil that I found to be absolutely incredible. It’s a crab claw from long ago which has completely turned into opal!

Now, from what I’ve learned, opalized fossils are not all that rare. However, an opalized crab claw that’s completely intact is quite rare, which makes this find even that more interesting.

According to, Opal generally known to form inside cavities within rocks. But if a cavity has formed as a result of a bone, shell or pine cone being buried in the sand or clay that later solidified and became rock, and the conditions were right for opal formation, then the opal forms inside that cavity instead. The result is a fossil replica of the original object that was buried.

More common types of opal fossils you would see are from partial structures such as bone, seashell or wood (petrified wood).

Ammonite shells are a more common type of opalized fossil.

Final Thoughts

What’s the most interesting fossil you’ve found? I think stumbling across an intact crab leg that’s turned into opal would probably be a lifetime high!

Be sure to check out some of the other interesting things from around the internet that I’ve stumbled across! And when you do, please share it with others who love these interesting kinds of finds!

Interesting Things From Around The Internet #1: The Scorpion That Turned Into Copper

Interesting Things From Around The Internet #2: The Worlds Largest Geode

opalized crab leg

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The Worlds Largest Geode (And How It Was Found!)

How Much Are Geodes Worth? (And Where To Sell Them)