Mercury (planet)
Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like Earth. It is the smallest planet in the Solar System, with an equatorial radius of . Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede and Titan. Mercury consists of approximately 70% metallic and 30% silicate material. Mercury's density is the second highest in the Solar System at 5.427 g/cm, only slightly less than Earth's density of 5.515 g/cm. If the effect of gravitational compression were to be factored out from both planets, the materials of which Mercury is made would be denser than those of Earth, with an uncompressed density of 5.3 g/cm versus Earth's 4.4 g/cm.
Discheramocephalus minutissimus
Discheramocephalus minutissimus is a species of feather-winged beetle, the smallest beetles on earth, first found in Indonesia. This species' adults have a body length of approximately 400 to 426µm. According to Grebennikov, the main factor limiting miniaturisation of female insects is an egg size significant enough in size to produce viable larvae. This size threshold is sometimes overcome, reaching limits of 180 and 130 µm in females and males, respectively, according to the author. Brain size is possibly the second most important factor limiting miniaturisation in this class.