I never have in all my years of exploring beaches and tidal pools. Does anyone know what it is?
E.J. Lefavour
http://www.hobbithousestudio.com
Joey Updates-
From Wikipedia-
Libinia emarginata is roughly triangular in outline and very heavily calcified, with a carapace about 4 in (100 mm) long and a leg span of 12 inches (300 mm).[4] The whole crab is khaki, and the carapace is covered in spines andtubercles,[5] and, as with other decorator crabs, often clothes itself in debris and small invertebrates.[4]
Good Morning Gloucester 
I’m no expert, but looks like a spider crab to me.
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It’s a decorator crab. They reach back and out seaweed and mud on their she’ll for camouflage
Check it out here on wikipedia
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Which is exactly why I’m not the expert!
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It is a common spider crab (Libinia emarginata). They are very common locally, but tend to stay subtidal. Joey’s right about them being a decorator crab, they have hook-like setae (hairs) that cover their carapace and legs that enable them to “velcro” algae, hydroids, anemones etc. to help them camouflage. We have a whole bunch of them here in the aquarium. As crabs go, they are pretty lethargic and not very aggressive.
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looks like somebody called it ‘lunch’
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OK, thanks everyone. I never heard of a decorator crab or a spider crab, and had never seen one before. Thanks.
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It may be a cousin to the spider crab but the spider crabs in deep water rocky bottom is similar but looks like a smaller version of a Alaskan King Crap and better tasting meat in legs than Lobsters……. Sorry Joey
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In the deeper waters 50-250 + fathoms (300-1500 ft+) there are strange looking craps and fish that most landlubers never see. That’s the home of the sea mobsters.
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