Where do Bone helmets drop? (or any notable item bases for that matter)

Hi! I would love some clarification on how this works. I checked the wiki (https://pathofexile.gamepedia.com/Bone_Helmet), and one of the maps it drops in is Underground river (https://pathofexile.gamepedia.com/Underground_River_Map). that's awesome, I thought to myself, place also drops hunter's reward div card, so I'll use my elder orb on it and farm it as much as I can.
Thing is - I never found a single bone helmet so far, nor have I found Gripped gloves (which also supposedly drop), but I did find spiked gloves(which do not show up in the list). Does elder orb change map-specific drops? do map-spesific drops change every patch and the wiki is not updated? am I just unlucky? I would love some clarification on this. (So that I might elder orb and farm a better, more suitable map)

Curious myself, other than the wiki (which has a lot) I only found this.

https://www.reddit.com/r/pathofexile/comments/869uey/psa_you_can_use_the_compass_on_the_atlas_to/

There's been changes to the atlas since then, so not positive it is current. Note he claims shaped maps don't give red tier bases. Assuming it was correct then it could have changed as well.

From my experience, I've seen Bone Helmets drop all over the place, but if you run maps that have skeletons you're 99% guaranteed to get 1 or more to drop.
Bone Crypt, Cursed Crypt, Seuplchre, etc...

The comnpass link is basically right. The maps in each quadrant change every league but which quadrant drops which bases never changes.

So you just look at his image (or google 'poe atlas bases' and a ton of images pop up) and look at your desired base to identify your target quadrant and then look at your atlas to see map options.

For what its worth, it def looks like Convoking wands share the bone helmet quadrants but I may be wrong on that.

~Myth

Thanks! apparently Underground River is outside the Bone helmet quadrant this time, and that's the reason it dropped. Didn't know about the compass thing. The more you learn ^^
TY all. gonna run bazaar and maybe get some saint's treasure ^^