No - or, not "only" six. Lobsters belong to the order Decapoda (literally, 'ten feet'), an order of crustaceans within the class Malacostraca. Remember that the "legs" may have significant specialization and not necessarily resemble a process that the organism uses for walking - such as swimmeretes, or front claws; in this case it might seem the lobster has four pairs of legs for walking (pereiopods) and one pair for grasping and manipulating (chelipeds).
It has 3 joints.
They have 1,000,000 joints
5
8
There are three joints in the human leg: the hip joint, the knee joint, and the ankle joint.
In the leg itself (disregarding either end of the leg), one; the knee joint.
muscle
Their joints are restricted, so around 5 or 6, given they walk sideways
a lady bug has 6 legs.
to move
The leg has a joint at the knee, one at the hip, and one at the ankle. So each leg has 3.
I do believe the joint in the middle of your leg is your knee.