https://en.wikipedia.org/wiki/Galaxy_filament

with a concrete rendering at

https://en.wikipedia.org/wiki/Void_(astronomy)#/media/File:S...

and some more at

https://en.wikipedia.org/wiki/Observable_universe#Walls,_fil...

These filamentary luminous matter distributions (and the sparse, dark, cold voids between them) drive our theories of structure formation:

https://map.gsfc.nasa.gov/universe/bb_cosmo_struct.html

There are some patterns at scales of up to a few tens of megaparsecs, but beyond that matter is for all practical purposes homogeneous and isotropic: with a good enough (infrared- or radio-) telescope you will observe a galaxy or a precursor along every line of sight unobscured by objects within our own galaxy, and only the reddening and dimming from the metric expansion of space permits any darkness at all in our sky.

This is important to the standard mode of cosmology, \Lambda-CDM, which relies on Friedmann equations, which model all the matter content of the entire universe (past and present) as a perfect fluid of uniform dust. Because of the "local" nonuniformities like filaments and voids, grains of dust are thus on the order kilo- to megaparsecs. If we find that there are bigger grains, the standard "concordance cosmology" will have to be adjusted to be concordant with the new large-scale evidence.

(There is lots of looking right now, but so far everything points to smoothness at scales much smaller than gigaparsecs, kinda how a sheet of paper looks smooth in your hands, but a tiny piece of it under a light microscope looks very fibrous, and under an electron microscope one might discern the remnants of plant cells, or even see microbes!).

The patterns it sees are real, and very cool.

https://en.wikipedia.org/wiki/Wilkinson_Microwave_Anisotropy...