Origin: L. Seamrog, seamar, trefoil, white clover, white honeysuckle; akin to Gael. Seamrag.
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... you compared it to a Marbled Orb Weaver? They are often variable in size and coloration. Thanks for the reply. It's similar to the Marbled. The Shamrock Orb Weaver, linked above, is almost identical, excepting for color and some marbling as you pointed out. It's harmless, thankfully.
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