Eyes On The Ground

List of locations:

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• [object=223193] - Unlike the others in the list, these clams are somewhat rare I found only a few so far. Generally, you can find the clams deeper and farther into the sea, often within the reach of Fatigue line. Some coords: 16.7-62.6; 47.9-87.9; 18.8-20.3
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• [object=222684] - Around all the shores of Timeless Isle. Both inside and outside the water.
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• [object=222685] - These common nests can be found basically anywhere in the jungle areas, near trees, bushes where cranes are nearby.
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• [object=222686] - Inside the Cavern of Lost Spirits, north of the central arena.
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• [object=222687] - Around Ordon populated areas, mostly in Firewalker Ruins.
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• [object=222689] - Around in and outside Ordon Sanctuary, the topmost hump of the isle, where [npc=72057] resides. Also around the Blazing Way, near to [npc=73307].
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• [object=222688] - On the cliffs and ledges of Ordon territories, those places are often hard to reach, best way is to descend from a [npc=73531].
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Found on at 18.65, 53.72, between shelf of one rock and the one beneath.

I found one Giant Clam @ 25.65, 14.49 & the Fiery Alter of Ordos @ 75.03, 44.73 directly in front of Speaker Gulan.