The weakest thing on Earth is soapstone which is one of the easiest to crush and break minerals.
Soapstone is a talc-schist, which is a type of metamorphic rock.
It is composed largely of the magnesium rich mineral talc.
Soapstone is nonporous and nonabsorbent, which makes it a good material for kitchen countertops and sinks.
It is also used for insulating electrical components due to its low electrical conductivity.
Soapstone is also used for construction of fireplace surrounds and with metal wood stoves.
Soapstone is relatively soft because of its high talc content, talc having a definitional value of 1 on the Mohs hardness scale.
Softer grades may feel similar to soap when touched, hence the name.
Soapstone is found throughout the world in relatively small deposits ranging from small rocks to seams, boulders and other deposits.
Soapstone is found in the Appalachian range from Maine to Georgia with significant deposits in Vermont and Virginia.
As for the weakest living things on earth.
Weakest Snake Venom: The Copperhead.
Weakest Mammal: Sloths.
Weakest Jumper: Elephants.
Weakest Turtle Shell: Spiny Softshell Turtle.
Mammal with the Weakest Eyesight: Star-Nosed Mole.
Weakest Flight: The Wild Turkey.
Overall Weakest Creature: Humans.