Puro-Puro (obtained in the Impetuous Impulses Minigame) or the full RuneScape world. Requires 65 Hunter.
Uses:
Can be looted to obtain a variable item and re-obtain the Impling jar (if it doesn't break).
Can be exchanged for rewards with the Elnock Inquisitor.
Notes:
Can be caught without a net (bare-handed) and without an impling jar outside of Puro-Puro.
In Puro-Puro you must have an Impling jar and Butterfly net or Magic butterfly net to capture implings.
Can be stolen by the guardian imps in the Puro-Puro plain.