Dried Betel nuts/ Viet Nam betel nuts

Betel nut is the small fruit of the areca palm, so it's also called areca nut. 
It is commercially available in dried, cured, and fresh forms. While fresh, the husk is green and the nut inside is so soft that it can easily be cut with an average knife.
In the ripe fruit, the husk becomes yellow or orange and, as it dries, the fruit inside hardens to a wood-like consistency. At that stage, the areca nut can only be sliced using a special scissor-like cutter.
They can be chewed for their effects as a mildly euphoric stimulant, attributed to the presence of relatively high levels of psychoactive alkaloids. 
Chewing increases the capacity to work also causes a hot sensation in the body, heightened alertness, and sweating.

In China, East and North-East India areca nuts are not only chewed along with betel leaf but are also used in the preparation of Ayurvedic and Traditional Chinese medicines.
Powdered areca nut is used as a constituent in some tooth powders. Other medicinal uses include the removal of tapeworms and other intestinal parasites by swallowing a few teaspoons of powdered areca nut, drunk as a decoction, or by taking tablets containing the extracted alkaloids.