I've shown you Mangda before (listed in the Meat Fish Eggs category of Appon's Thai Food - I didn't quite know how to classify it!), the large insects pounded into a chilli-paste and used for flavorings. This is the far less intimidating version, 'Mangdana Essence', an extract or often a synthetic replacement flavouring that you can buy at your Asian grocers.
It comes like this, a tiny bottle of essence with a dropper to be used very sparingly.
We add this to nam prik and similar pastes to enhance the fragrance. It has a sweet floral, almost peppermint smell, not at all what you'd imagine. With most of the flavour being light notes that evaporate quickly it's added as one of the final ingredients.