Here's a creation I came up with several years ago, before I even joined this site, if I recall.
If you pile up enough microscopic organisms, does that pile become visible to the naked eye...?

Necrochainers are mysterious microscopic creatures residing in pocket spaces between dimensions.
They travel in swarms in such great numbers, it appears as a purple cloud.

Necrochainers devour anything in sight, which looks like objects disintegrating to the average person.
However, Necrochainers are not of malicious nature, and usually do not come to inhabited dimensions.

The purpose of a Necrochainer is to restore balance to the omniverse through destruction. If something happened that upset the balance of the omniverse, a swarm Necrochainers is released upon an uninhabited universe to devour enough planets in an attempt to offset that imbalance.

Necrochainers can be seen as nature's way of restoring balance where natural disasters aren't enough to do so. Considering they are unstoppable and can devour any matter and reduce entire universes to absolutely nothing, it truly is nature's last resort to unleash a swarm on the universe where the imbalance originates from if it's an inhabited universe.

They're a blue-ish purple with red eyes.