Researchers discovered a 100-million-year-old piece of amber that may be the oldest evidence of sexual reproduction in a flowering plant, according to a news release.

The amber holds a cluster of 18 tiny flowers from the Cretaceous Period, which are now extinct.   According to researchers, the plants found hold the same reproduction process that flowering plants, or "angiosperms," have today.

"In Cretaceous flowers we've never before seen a fossil that shows the pollen tube actually entering the stigma," George Poinar, Jr., a professor emeritus in the Department of Integrative Biology at the OSU College of Science, said in a news release. "This is the beauty of amber fossils. They are preserved so rapidly after entering the resin that structures such as pollen grains and tubes can be detected with a microscope."

The flowers are reportedly in "remarkable condition" and is one of the most "complete" clusters ever found in amber.  According to the researchers, the flowering plants at the time were "quite small."

Poinar said the pollen of the flowers appeared "sticky" which suggested they were carried by an insect, according to a news release.  The fossils were found in amber mines in the Hukawng Valley of Myanmar, previously known as Burma,

"The evolution of flowering plants caused an enormous change in the biodiversity of life on Earth, especially in the tropics and subtropics," Poinar said.

"New associations between these small flowering plants and various types of insects and other animal life resulted in the successful distribution and evolution of these plants through most of the world today," he added. "It's interesting that the mechanisms for reproduction that are still with us today had already been established some 100 million years ago."

Click here to read more information about the 100-million year old flowering plants found in the amber fossil.