These are phenolic resin also known as "African Amber". It is a man made plastic similar to Bakelite in that it is an early plastic first made in the 30's. Europeans would trade these for ivory and gold.
They were made to look like amber and used like currency by Africans.
measures approx : 1" 1/8 diameter by 3/4 h
weight 1.3 lbs or 500 grams