Identify the location and function of the following structures in an earthworm:
$(i)$ Setae
$(ii)$ Typhlosole

(N/A) $(i)$ Location: $S$-shaped structures made of chitin found in the body wall (epidermis) of the earthworm.
$\Rightarrow$ Function: They provide grip in the soil and assist in locomotion.
$(ii)$ Location: It is an internal median fold of the dorsal wall of the intestine,starting after the $26^{th}$ segment.
$\Rightarrow$ Function: It increases the effective surface area for the absorption of digested nutrients in the intestine.