Wikipedia has a more detailed approach to the definition over here.
There were a number of types of animals and forms used for Aquamaniles. There have been lions, rams, people, birds and many others. I guess you can even think today's cow creamer is a cousin to the aquamanile in a way.
This one I recreated was a Deer that was found in Rye, made sometime between 1300-1399.
Mine is on the left and the original (leg less... appendages usually break off in use or buried over time from pressure) on the right. The original info from the VA is over here.
These ceramic objects are always fun to show off.