For many creature design ideas with based on science inspiration, their biology requires a way to produce high pressions into their body with the aim of pressurizing gases or containing some other substances in a specific state, that otherwise could not be used. For example in some answers of How could I scientifically explain ice breath?, How a living creature could produce "bio" aerogel? and Could a living creature produce graphene?, could be required preserve determined material at high pressure either to increase the temperature or prevent it from evaporating or or in fact it may be that the advantage of the great internal pressure is to release it to expel some material with great force.
The point is that many of these creatures require the ability to generate great internal pressure in some organ to carry out their almost fanciful capacities, a characteristic that is not explained in sufficient detail in their original publications.
So, how a living creature could develop to have into its body an specialized part to generate high pressures, and keep them for a relatively long time and then release this pressure with whatever material has been stored at will?
Edit. For more information I want to be based in the ice breath of 56 atm for keep CO2 liquid at 20 °C, so for temperature variations I think 100 atm is the superior limit for this. But also I would like a pressure in which the required supercritic state for aerogel production could appear, but I dont know which is the required pressure for this, I will assume that is the same as water 22-26 atm but I dont really know.