Extremophiles are animals that can or need to live in extreme environments. Some of the most famous ones are Tardigrades (aka Water Bears) which have been proven to be able to survive being exposed to the vacuum of space. The thing about Tardigrades, though, is that they are extremely tiny, usually reaching a size of about 0.5mm (0.02in). There are other extremophiles, like the Rock Crawlers that are a bit larger.
Rock crawlers are a type of wingless insect that grows to between 15 and 30mm long. They have both cricket and cockroach characteristics which gives rise to their scientific name - Gryllobattidae. "Gryll" is Greek for cricket, while "blatta" is Greek for cockroach. They either have primitive compound eyes or none at all, which they don't need since they are mainly nocturnal. There are currently 25 species known to science, of them 11 of them are found in North America. The antennae are known as filiform, which means that each segment in the antenna is the same width as all the others, so there is no tapering over the length of the antenna, much like a cockroach. This is different to stylate antenna found in robber flies for example, that taper and end in a sharp point.
As mentioned earlier, there are 25 species currently known to science and all are found in the northern hemisphere. The first Rock Crawler or Ice Bug was discovered in Banff in Alberta, Canada in 1914. What makes them extremophiles though is their love for extreme cold. These interesting creatures live in the high mountains and in the coldest climates. There is even a species that has been found in Siberia. In fact, they are so perfectly adapted to the cold, in fact, that the species found in Banff, if picked up and held in your hand, will die of overheating just by the heat given off. The bugs will die if their temperature goes above 10C. For this reason, Rock Crawlers are mainly nocturnal and therefore have very basic compound eyes, if they have any at all. According to W.R. Henson in an article published by Nature on 23 Mar 1957, the Rock Crawlers seemed to prefer a temperature of about 1C and fully saturated air. This means that the air holds as much moisture as it possibly can. (Source)