Who we Are

Jocelyne DiRuggiero is a professor in the Department of Biology at Johns Hopkins University in the US. Her lab's research focuses on the stress responses of extreme microbes and on the ecology of extreme environments. You can read more about the research at the lab's website.

Microorganisms have inhabited the Earth for 3.4 billion years of its history. They are essential for the evolution of its minerals, its major geochemical cycles, and its atmosphere, yet the extent of their diversity remains vastly unexplored.

Understanding the link between the geochemistry we observe and the impact of microbial activity is critical if we want to learn more about our own biosphere and how to better conserve and protect the environment from climate change and increasing desertification.

Planets and moons we have explored so far, such as Mars, harbor extreme environmental conditions with similarities to some of the most remote and punishing place on Earth. It therefore makes sense to study microorganisms that live in extreme environments, such as extremely salty places and very dry deserts if we want to learn more about the type of life we might found elsewhere in the Universe.

Why we Need You

We are currently analyzing rocks that we have obtained on expeditions to the world's deserts. These expeditions have produced lots of excellent samples, but we need more data in order to answer our big questions. We want to supplement our collection with your finds.

There are particular regions of the world that we are interested in obtaining samples from. Every continent has extreme deserts, and if you live near one you may be able to collect the kinds of samples we're looking for.

If you sign up and send us pictures of your finds, we will let you know if we want you to send them to us. Once the rocks get to our lab, we will study their geochemistry and, using molecular methods, identify the microbes inhabiting them. You will be able to see whether data obtained from your samples are used in journal publications or shared at conferences. If you want to know more, you can visit our website.

Rock Reference Library

In order to find the kinds of samples we're looking for, you'll have to get acquainted with the basic types of rocks. Don't worry, it's not hard - we have put together a reference guide for you.

Here are some examples of the rocks we are interested in and how to recognize them. Of course, we cannot be really exhaustive, and there are probably many rocks you could add to our project! A description of the type of colonization can be found in our Colonization Zones Workshop.


The calcite rock is a calcium carbonate (CaCO3) rock, similar to limestone and dolomite. It is a very hard rock so you will need to break it with a hammer to look inside!

In the field, the calcite rock occurs as layered deposits. You can find several type of habitats within calcite rocks: the endolithic habitat, which can be a thin (few millimeters) to a thick green colonization (few centimeters) under the surface (blue arrow), and the hypolithic habitat, which looks like a green layer on the underside of the rock and in contact with the soil (red arrow).


The granite is a typical igneous rock that forms by crystallization of molten material. It is a coarse-grained and hard rock that displays a large variety of colors.

In the field, the granite rock is patchy distributed in the outcrop along with other substrates. The colonization type is endolithic, with an intense green color.


The gypsum rock is a very soft rock, composed of calcium sulfate (CaSO4∘2H2O) that forms as an evaporite around clay beds. To recognize a gypsum rock, you can easily scratch it with your fingernail, and these rocks are generally light in color.

In the field, the gypsum rock appears as massive evaporite deposits. The gypsum rock display several types of habitats for the microbes, mostly as very thin green layers (few millimeters): the endolithic habitat, where the organisms colonized the rock just underneath its surface (blue arrows) and also the hypoendolithic habitat, within the underside of the rock (yellow arrow). Sometimes, the endolithic colonization displays green and orange layers (green arrow), with the orange layer between the rock surface and the green layer.


The halite is a soft evaporite formed by precipitation of sodium chloride (NaCl), as the water in a salty lake or lagoon dried out. Recognizing halite is easy: it has a salty taste! Also, it looks like you table salt when you break it.

In the field, halites look like nodules with strange shapes and are sometimes covered by dust. The colonization type in halite is mostly endolithic: it occurs as a green and diffuse zone inside the rock (blue arrow).


The Ignimbrite is a hard, volcanic rock that consists of crystals and rock fragments welded together. It is a fine-grained colored rock, rich in quartz and feldspar grains, sometimes accompanied with mica and other minerals.

In the field, it occurs as an outcrop and is sometimes found in association with gypsum rocks. The colonization type is mainly endolithic and occurs as a very thin intense green layer just under the surface of the rock.


The quartz is a very hard and common mineral that can display a large variety of forms and colors. It is an oxide silicate, mostly transparent or translucent.

In the field, the quartz rocks are randomly distributed on the ground and their sizes vary from less than 1 centimeter to a few centimeters. The quartz is a perfect example of a hypolithic habitat (red arrow), where the microorganisms are located on the underside the rock and in contact with the soil (orange arrow).


The sandstone is a common medium-grained sedimentary rock. It is composed of accumulated quartz grains associated with feldspar, mica, and other minerals. It displays a variety of colors from ochre to red.

In the field, it occurs as large deposits, forming cliffs and canyons. The colonization type is mainly endolithic, with a thin green layer underneath the surface. Colonization of the "yellowish" rock is the most common, while the red sandstone is rare.