This jar was born out of a joke with myself,

thinking of how a leech is so undesirable through medically crucial. Thinking of the prominence and history of leech medicine, this jar is depicting a style of jar from a time period when leeches were most desirable, as a cure-all and status symbol for physicians.

The holes in the top of the jar allow them to breathe.

In modern day when a leech is used on a patient, it is removed from storage, placed upon a patient for an allotted amount of time, and immediately disposed of. 

Vessel referencing an 17th century Alcock-type Leech Jar.