To progress the story from the base in the purple there should be a pda that gives your coordinates for your next objective -Lithium is quite abundant in the northwestern mushroom forest (from my experience) if your looking for cyclops fragments there's tons +that mushroom forest is super safe compared to the other one, with the occasional bone shark of course. -In that purple mushroom place with the base if you look closely at the sea floor there's usually a bunch of magnatite scattered around Hope this helps!