Your shop is extremely niche with a lot of very sciency terms that most shoppers won't understand.
It's good to have some very specific terms, but you'll want to have broader keywords as well to draw more casual collectors who don't know the specific terms.
Put the broader terms at the front of the listing, and the more specific information towards the back. Right now a casual browser will only see the first few words. For example, "White Carboniferous Reticulopteris", which 99% of people have no idea about.
Example listing title:
"Rare Fossil Fern Specimen, White Carboniferous Reticulopteris, Large Collectible Paleozoic Plant, 2 Sided Display Piece"
Your descriptions have too much white space. This:
"Age:
(~305 m.yo)
>Paleozoic Era"
Would be better as:
"Age:
~305 million years old
Paleozoic Era
Upper Carboniferous/Middle Pennsylvanian"
State measurements in your description. Say how you will safely pack it. Maybe talk about what kind of plant it was when it lived, what it co-existed with (like dinosaurs or the first mammals). Give more information to draw in the buyer.
The description also gives search engine clues as to what the item is, so you should say something like:
"I hand mined this fossil fern specimen and carefully prepared it for display. It will make a great gift for a botanist or rock collector, a wonderful Father's Day gift. Excellent decor for your study or university office."
Tags should literally describe the item in 2 - 4 word phrases or collections of words that literally describe the item for sale.
NO single word tags - fill all 13 tags and 20 characters with unique search terms.
NO repeats - they are unnecessary because the search engine automatically draws from every tag to match the search query.
NO words that don't literally describe your items - they will drag your item further back in search results. For example, you aren't selling "dinosaurs" or "archaeology".
Some examples for that listing:
"large plant fossil", "White Carboniferous", "Reticulopteris Fern", "2 Sided Display", "fossilized plant", "rare collectible", "collectable specimen", "man cave decor", "professor present", "Father's day gift", "rockhound decor", "prehistoric flora", etc.
https://www.etsy.com/legal/policy/search-advertisement-recommendation/899478564529
https://www.etsy.com/seller-handbook/article/366469415790
