I urge everyone to bookmark that blog; it is always a fascinating tour of the weirder and wonderfuller places on our planet. And let me leave you with this simply jaw-dropping video of undulatus asperatus in action.
(A sunscreen with a physical block like titanium dioxide or zinc oxide can be applied last, after a serum or moisturizer.) Apply a serum next and, finally, moisturizer if you need it. Polis also recommends serums or sunscreens with moisturizers built in because they save time.
Again, there is not a definite answer on this, but considering that chemical sunscreens need to be in contact with the skin to work and physical blockers are better applied before moisturizer too, I think it makes sense to apply this type of sunscreen first too.