Turn the aerator housing counterclockwise and remove it from the faucet. Pull the O-ring off the tip of the faucet spout with your finger. The O-ring prevents leaking between the housing and the faucet. Set the O-ring in a safe place until you are ready to reinstall the housing.
After that, they are referred to as yearlings or stirks if between one and two years of age. A castrated male is called a steer in the United States; older steers are often called bullocks in other parts of the world but in North America this term refers to a young bull.
The terminology described here contrasts the differences in definition between the United Kingdom and other British influenced parts of world such as Canada, Australia, New Zealand, Ireland, and the United States. An intact (i.e., not castrated) adult male is called a bull. A wild, young, unmarked bull is known as a micky in Australia. An unbranded bovine of either sex is called a maverick in the USA and Canada. An adult female that has had a calf (or two, depending on regional usage) is a cow.