Baskar River (there are many possible spawn locations)
Beavers are the best solution to gaining cementing paste. Cementing paste is a real pain to craft as it takes crazy amounts of stone and chitin. The dams are also great for getting a fair amount of wood, if you don’t have to travel too far with all the weight. The other good resources are the silica pearls, which is nice if you have a base away from the ocean, or just need a few really quick. Casteroides themselves are great for harvesting wood, as you would imagine, and can be used as a smithy, which might be handy for some.