Sacred clay pouches (class 1) are made by using class 1 sacred clay on a Creation kiln. They can be made with level 1 summoning and require level 1 summoning to use. The familiars summoned have 1 beast of burden slot and a special ability that banks the items within its inventory. This is the weakest of 5 variations.
When you die any familiar you had summoned will disappear and will drop any items they were holding on the ground where they were standing when you died. Many players, particularly mages, though theoretically anyone could use this tactic, use familiars to their advantage in this situation. When the familiar disappears and drops the items it is holding the items, for a short time the items are only visible to you (similar to if you were to drop the items yourself). For this reason many mages use familiars to hold extra runes so that if they die they can run back, pick up the runes, and resume fighting without having to make more.