Finding every Mokoko Seed in a Lost Ark map can be pretty tough. This objective is exacerbated by the fact that different areas hide their seeds in very different ways. Where overworld maps throw gobs of open space at you and challenge you to find a few needles in a giant haystack, dungeons tend to be dense with seeds that are hidden behind tricks and tests. True to form, Gray Hammer Mine leaves a few seeds out in the open but hides several others out-of-bounds while limiting your ability to backtrack.
The majority of the in-bounds Mokoko Seeds in Gray Hammer Mine are straightforward to pick up once you know where to look. The only exception is the seed just before you get in the mine cart. It’s not hard to find, but it’s easy to accidentally get in the cart before you get it. If you do miss it, you’ll have to start the dungeon all over again to pick it up.
As for the out-of-bounds seeds, the first one (not circled on the above map) is simple once you find the hidden entrance, which will require breaking a couple of destructible objects in the area. The seed circled in blue takes a little more work. For this, you’ll have to head to the hidden area circled in red, where you can pick up two more seeds and a lantern.
Once you have the lantern, head back to the first hidden area and place it on the pedestal. This will illuminate a path through the fog that will take you to the seed on the other side.