Panspermia previously thought to be inhospitable for life. Living bacteria found in ice core samples retrieved from deep at Lake Vostok in Antarctica, have provided data for extrapolations to the likelihood of microorganisms surviving frozen in extraterrestrial habitats or during interplanetary transport. Also, bacteria have been discovered living within warm rock deep in the Earth's crust. In order to test some these organisms' potential resilience in outer space, plant seeds and spores of bacteria, fungi and ferns have been exposed to the harsh space environment. Spores are produced as part of the normal life cycle of many plants, algae, fungi and
Brown algae preserve only a flattened outline, without the microscopic features that permit the major groups of multicellular algae to be reliably distinguished. Among the brown algae, only species of the genus "Padina" deposit significant quantities of minerals in or around their cell walls. Other algal groups, such as the red algae and green algae, have a number of calcareous members. Because of this, they are more likely to leave evidence in the fossil record than the soft bodies of most brown algae and more often can be precisely classified. Fossils comparable in morphology to brown algae are known from strata as