Adamant Beetle appears in the second half of the Arqa Block in Tartarus, from 41F onward. Since it is a lone Shadow in the battle area, it will appear as a smaller Shadow crawling along the floor.
Adamant Beetle appears in Marukyu Striptease on the Midnight Channel, on floors 7 and 8. Upon being defeated, it may drop Safety Angle. Collecting and selling 10 of these will unlock the Tranquil Buddha accessory at Daidara, which reduces the chance of a party member being afflicted with Confusion.
In Golden, it appears on floors 7 through 10. It may drop Fluorite for trade at Shiroku Pub.
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