Rare 'dragon eggs' hatch in Slovenian cave

File photo - a Postojna Cave olm (Postojnska Jama Cave-Grotte-Hohle).

File photo - a Postojna Cave olm (Postojnska Jama Cave-Grotte-Hohle).

An unusual event is happening at a cave in Slovenia as rare salamanders hatch from so-called “dragon eggs.”

The pale, blind salamander, known as the olm or proteus, only reproduces every 5 to 10 years, and is thought to live to 100, according to the BBC. Olms, which are called "baby dragons" by locals, typically grow to between 8 and 12 inches.

"We got our first Baby dragon!" the Postojna Cave posted on Facebook Wednesday.

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The BBC reports that another baby olm was making its way out of its egg Wednesday. There are another 21 developed eggs in an aquarium at the Postojna Cave, which is a popular tourist attraction.

Originally there were 64 eggs, which were laid by a single female over a period of weeks, according to the BBC, which notes that only 23 embryos developed. The first egg was noticed in January.

Two years ago, a Postojna olm also laid eggs, but they fell prey to other cave inhabitants. So, this time biologists isolated the female and her eggs in a dark spot, added extra oxygen and removed any outside influences.

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Native to the underground rivers of the Balkans, olms have long fascinated scientists, included legendary naturalist Charles Darwin, who discussed the creatures in his famous “On the Origin of Species.”

The Associated Press contributed to this report.