Calabash pipe shapes comes from the original gourd / calabash. The meerschaum insert on the gourd pipes give this mushroom shape. All pipes mushrooming at the top called as calabash pipes or calabash design. You can find a large selection of calabash pipes at your store. Not only the mushroom shape of gourd meerschaum pipes name this model; "Reverse Calabash" pipes or "RC" pipes called calabash as well. They don't have that mushroom look but they have the original gourd calabash smoking effect. RC pipes have the same empty room for smoke to cool down. RC pipes have this empty room for smoke to settle down in their wide shanks.