Gastrulation

Embryos begin as a single fertilized egg cell which divides a number of times to form a ball of cells known as a blastula. The ball is usually composed of a layer of cells on the outer surface which totally or partially covers the yolk or some other liquid. In the particular case of the sea anemone Nematostella vectensis, which we are currently investigating, the blastula is roughly spherical and is composed of a single layer of cells which encloses and seals an internal cavity called the blastocoel which is filled with a yolky mixture.
Animal tissues can be divided into three types: endoderm, mesoderm and ectoderm. Simpler animals, such as Nematostella, only have two tissue types as they lack mesoderm. The process by which the embryo organizes itself into these distinct layers is called gastrulation and is present in some form in all animal development. Gastrulation involves a large reorganization of the blastula into the folded form of the gastrula. Although each cell moves independently without any central control, the blastula is reshaped in a coordinated way.

Stromatolites

Stromatolites are "living rocks" found in shallow waters. They grow due to the microorganisms that inhabit their surface, onto which they cement layer upon layer of sediment. It is a slow process and may take hundreds of years for a stromatolite to reach the height of your knee. They are weaklings, easily destroyed by all sorts of marine life. But they've come a long way. They've been around since the beginning of life on Earth. And they might just prove that life once existed on Mars.

Stromatolites have been on the Earth virtually since the appearance of the first microbes. They dominated underwater landscapes for much of Earth’s history, leaving behind a rich fossil record, sometimes revealing enormous reefs that were built long before sponge or coral even came into existence. Stromatolite frequency declined as diversity of life exploded and today only a few groups of 'living' stromatolites can still be found growing, almost always in special environments.

Ancient stromatolites are very diverse and more than a thousand taxa have been identified over the last hundred years. This diversity arises from the enormous number of biological, geological and chemical factors which may affect their growth. In the case of the most ancient stromatolites, questions have arisen over the role of biology in their growth. Microfossils are almost never conserved the these specimens and it is often difficult, if not impossible, to prove that the microorganisms were even there, let alone built the structures.

In order to help assess whether a stromatolite is biotic, we have chosen to model the microorganisms that build the most impressive stromatolites: filamentous cyanobacteria. From a model of individual filaments, we attempt to simulate the "birth" of a stromatolite. In further research we will attempt to study the effect of cyanobacteria on shaping laminae and also the interaction between the cyanobacteria and other processes.