Turtlie

Turtlies are any number of cosmological objects, vastly ranging in size from sub-universal to universal, based on the famous saying, "it's turtles all the way down". They can a collection of lower-level Turtlies, being made of even smaller ones and so on, except if they are the lowest-level Turtlie, the Planet. Higher-level Turtlies are always made of the previous level, except if they are a Planet.

There is also a measurement system used by many civilizations within The Infinite Cosmology that starts with T-0 (Planet), T-1 (Star System), etc. This is a set of values corresponding with their objects:

The Trutlie ranking system is has the same essence as the EUSI, the differences being, that the Turtlie counts the amount of nested systems, instead of physical containments, and doesn't include an array as its input.

The Turtile rank should theoretically begin with T-0 being a moon, but not all planets have moons, and if we include moons, there is nothing stopping moons from also having moons, and triple nested moons, and so on. This could theoretically be described as $$T-(-\omega)$$, but the author didn't intend for this originally, so it is unofficial yet.