Readed all answers and comments. Correction codes are in some. In some are question about structure and decryption that information.
Fractals, or at least principle is very useful. There are 3 images, click will open full image:
All tree images are kinda fractal in informational sense (hmm, if imagine that first one gray-white is made by 1-0)
second is connected to movies data, 3th to biology.
In same time, by them selfs, they show image encoding systems-approach, and if someone grasps fact that this is image, he just automatically will get knowledge about approaches we use to encode visual information.
Also interesting moment, faces will be recognized by humans, as long as they are humans. Not sure about million years trough, but assume it's about peoples.
For other species it will be tricky part to recognize that this is information (if we talk about primitive technologies, but even for advanced it may be a challenge, depends how we encode)
Nice thing about such approach, deep leveling information. It may be readable even for stone age peoples. Yes it will take some time for them to read it but, this information may guide them from beginning from stone axes to tunnel microscope.
Each layer is accessible on current level and describes access to next level.
This leveling structure is good also because of density of recording, it may totally consists from subatomic records, but still kinda be accessible from stone age tech (yes, they have to born concept of information as such, but not necessary consciously, sub-consciously will be ok too)
Probably I'm not original, also I would like to see more sophisticated approaches.
this Image is Voyager gold plate
As human born in our time and as one who is familiar with concept of plots etc. I have 3% clue what this picture have to mean. Long time I tried not to spoil meaning of that plate, and I think I almost did that(until first smart comment of course - no spoilers pls).
Time will come and I will imagine myself as alien civilization, which tries to guess what hell that means. (almost did that, f spoilers popped up - have to wait next 10y to forget). But those who do not know exact meaning may test them self.
Back to fractal knowledge. Roll out that knowledge is like learning, and this process may be compatible with human behavior, learning style. As small kid learns world, so will be such representation learned. Literary, it may be available almost from begin for a kid, as toy maybe and may lead him trough live to PhD in Physics.
My first experience of English was watching cartoons, although I learned that language barely enough to communicate, but still. But it may be not only vocal language, but also it have not to be mathematics just from start. Because mathematics as whole is also concept, existence of which it is a knowledge to be learned first by it's selfs.
Not sure if it will work on 1kk old humans, eventually it will, probably, specially if form of that storage will be handy to smash something.
There may be much more connections to human nature than just form or visual or even sound (natural frequencies of that storage as example), in data structure, what attracts our attention on refectory level and so on. It may be so specific to humans as whole, so it may be big challenge to other intelligent creatures to read that information without humans, and still be accessible from stone age level for humans.
That way storage may be as dense as it possible for civilization who records it, be cryptic for others, be accessible for those who have to read it, in wide range of their development and knowledge.