疋 正

pi/ya/shu

foot; a piece/roll

do not confuse it with 'right' 正 - the added stroke is for the knee (to the end of the 'foot')

木

mu

wood, timber, tree

楚

chu

clear, distinct;

pain, suffering

tree (mu) + tree (mu) + foot (shu)

to walk through lush, forested environment brings clear pain and suffering to feet 

虫

chong

insect, bug, worm

the original form depicted a viper (with a triangular head) - and snakes are a menace for all kind of insects

蛋

dan

egg

foot (shu) + insect/worm (chong)

only the feet of an insect can walk on eggs without breaking them