Final answer:
A nun buoy will have an even number and is conical and red in color, meant to be kept to starboard when entering from seaward according to the 'red to starboard' rule.
Step-by-step explanation:
A nun buoy will have an even number and will typically be colored red. It is designed to be conical in shape and should be passed on the starboard (right) side when proceeding from seaward into harbor (returning to port).
This is in accordance with the lateral system of buoyage used in the United States and many other parts of the world, which is part of the 'red to starboard' rule when returning from sea. The opposite would be a can buoy, which is cylindrical and marks the port side of the channel with an odd number and is usually green.