Trovants: The Stones That Move and Grow

A giant Trovant. Trovants such as these are found only in Romania and have become such a tourist attraction that they are protected by UNESCO. WIKIMEDIA COMMONS (CC BY SA 3.0)
These are Trovants, found only in Romania. They have become such a tourist attraction that they are protected by UNESCO. WIKIMEDIA COMMONS (CC BY SA 3.0)
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Have you ever heard of the moving, and growing geological formations known as trovants?

These are stony, bulbous and protruding boulders only found in a small town in Romania called Costesti. Local lore is full of stories that ascribe all kinds of powers to them, including the ability to grow, walk and even give birth to tiny little trovants.


These are the mysterious growing stones found in Romania, known as Trovants.

These are the mysterious growing stones found in Romania, known as Trovants. CC BY


Far-fetched right? Well, according to science, they may be right.

Trovants were described as concretions – mound of mineral matter that has been embedded within layers of limestone, sandstone or shale, usually found in sedimentary rock or soil.

According to “Consisting of a stone core with an outer shell of sand, after a heavy rain small forms are said to appear on the rocks leading them to be dubbed the “growing stones” by locals.”

They are usually spherical or sometimes slightly irregularly-shaped and can be as small as an inch (2.54 cm) in diameter, weighing only a few grams. However, they can also be gigantic, reaching lofty heights of 15 feet (4.5 meters) and can weigh several tons.

Since the 18th century they have have been a source of wonder for observers. In fact, people have variably thought of them as dinosaur egges, plant fossils and even alien transports.


Lanscapes in the Buzăului Mountains, Romania: trovant at Ulmeț

Lanscapes in the Buzăului Mountains, Romania: trovant at Ulmeț. Wikimedia Commons


In 2008 the International Geological Congress in Oslo decided that they were classified incorrectly as concretions. According to this, not only did they not have a nucleus or stone core (something concretions have), there was no mineral difference between the stones themselves and the sandstone beds on which they stood.

Scientists are of the view that they were shaped by earthquakes around 5.3 million years ago (at a geological time known as the Middle Miocene sub-epoch). And the reason that bivalve and gastropod fossils can be found in them is because the surrounding area was an ancient marine environment.

How do trovants differ from other similar geological formations?

Trovants are unique in that they “grow” through the infiltration and precipitation of mineral-rich water within them. In contrast, static concretions form around a nucleus and do not change in size.

What geological processes contribute to the growth of trovants?

Rainwater, carrying dissolved minerals, penetrates the porous structure of a trovant. This leads to mineral precipitation within the trovant. Over time, these minerals crystallise and accumulate in layers, gradually increasing the size of the trovant.


A trovant

A trovant. Art Anderson Wikimedia Commons


Can they grow, multiply, and walk?

The trovants absorb mineral from rainfall after a heavy shower. When these minerals come in contact with chemicals present in the stone, a pressure reaction occurs that makes the rocks grow. Unfortunately, this is not something we can see because it happens over many years. In fact scientists think this is roughly 1.5 to 2 inches (4 to 5 centimeters) every 1,000 years.

The mineral-chemical reaction also causes them to seemingly “reproduce” or multiply. When a new growth forms, typically from water affecting just one side of the rock, it can eventually become large enough to break off from the “parent” rock, resulting in the creation of baby trovants.

As for walking, well, there is only anecdotal observation for that. One researcher has said to have filmed trovants for two weeks and claims that one of them moved a tiny bit. Generally though, scientists do not think that they can walk or move. It is possible that heating or cooling of soil may cause some movement.

The “Muzeul Trovantilor” or Trovants Museum Natural Reserve, was developed in Valcea County, Romania, in 2004, and is now protected by UNESCO.

Worth a visit, no?




I am a Chartered Environmentalist from the Royal Society for the Environment, UK and co-owner of DoLocal Digital Marketing Agency Ltd, with a Master of Environmental Management from Yale University, an MBA in Finance, and a Bachelor of Science in Physics and Mathematics. I am passionate about science, history and environment and love to create content on these topics.