The universe is so big, if there is life only on Earth, it is estimated that no one wants to believe it, so in many science fiction movies, there are plots related to extraterrestrial creatures. For us humans, it is difficult to describe things that are completely unknown, so when designing the alien creatures that appear in these science fiction movies, people will more or less use some known creatures on the earth as prototypes, the most commonly used of which should be the octopus.
The main reason why people originally used octopuses as prototypes for imaginary alien creatures was because of their strange appearance, but with the deepening of the study of octopuses, people were surprised to find that the peculiarities of octopuses are not limited to their appearance, so that some scientists have put forward the idea that octopuses may not really be the "native fish" of the earth, and studies have shown that octopuses should come from aliens.
Let's start with their hearts, which have been shown to have three hearts, two of which are dedicated to their gills and one to their whole body (by the way, octopuses have blue blood).
Octopuses with 3 hearts are already very different, but they have a larger number of brains, a full 9, these 9 brains can be divided into 1 "main brain" and 8 "secondary brains", of which the "main brain" is located in its head, which is their nerve center, and the "secondary brain" is located in their eight brachiopods.
Normally, their "main brain" only needs to give a simple instruction, and the rest of the work is done by the brachiopods themselves, which greatly reduces the work pressure of their "main brain".
It is worth mentioning that the octopus also has a unique way of escaping, when in danger, they will often coil 6 of their 8 brachiopods around their heads, making them look as if they have a hard shell, which will cause some trouble to predators, and at the same time, the octopus will use the remaining two brachiopods to make a similar movement as we humans run, and in this way quickly avoid danger.
Another peculiarity of octopuses is that they have a number of up to 500 million neurons, such a high number, let alone other mollusks, even many mammals are far inferior, for example, the number of neurons in house mice is only about 80 million.
Everyone should know how high the IQ of house mice is, so it is natural that octopuses have extraordinary IQs. An IQ test experiment was once conducted on an octopus, which can be described as simply as: putting the food that the octopus likes to eat into a bottle, then tightening the cap, and then holding it in front of an octopus to see if the octopus can find a way to get the food inside.
The experiment was divided into three experiments: in the first experiment, the octopus spent a long time trying to open the bottle from all angles using its brachiopods, and finally unscrewed the cap in the correct way to obtain the food inside, and in the second experiment, the octopus directly used the correct method and quickly ate the food.
In the third experiment, the researchers added a new octopus, and this "novice octopus" used the same method to obtain the food in the bottle after witnessing the previous "veteran octopus" method of obtaining food.
There are many "smart moves" of octopus, if you are interested, you can search for relevant information on your own, so I won't talk about it here. It is important to know that these characteristics can only say that octopuses are very strange creatures, and the real reason why it is doubtful that they are not the "native fish" of the earth is the discovery of scientists at the molecular biology level, that is, octopuses can sacrifice the evolution of genomic DNA in exchange for a large amount of RNA editing.
To understand this, we can compare DNA to a production drawing, and then to a person on the production floor, who under normal circumstances would make a "product" - a protein with a specific function - strictly based on the "production drawing" of DNA, without altering it without changing it. In molecular biology, this is known as the "central law", which is followed by almost all organisms with a cellular structure, even us humans.
However, octopuses defy this rule, and within their cells, RNA often changes the "production drawings", and these "workers" do not modify it randomly, but adjust accordingly according to the current environment, and then make a more realistic "product", that is, protein.
We know that protein is an important material basis for life, and different proteins have different functions, so this mechanism of octopus can make them adapt to the current environment better and faster, but this mechanism has a big drawback, that is, it will cause 23% to 41% of genetic isolation, which will lead to a significant reduction in the evolution rate of the octopus genome.
So theoretically, the genome of an octopus should be much less complex than the average of other organisms, but in practice this is not the case, because scientists have found that the genome of an octopus is very complex, with about 33,000 genes, and even more than 10,000 more than us humans.
In other words, how can we explain the fact that the actual situation of the octopus is seriously inconsistent with theoretical expectations? A reasonable conjecture is that the octopus may not be the "native fish" of the earth, but should have originated outside the earth.
In fact, as early as 2018, Advances in Biophysics and Molecular Biology published a paper titled "The cause of the Cambrian explosion of life – Earth or Universe?", which was co-authored by more than 30 scientists, which clearly pointed out that the octopus may have originated from extraterrestrials.
The paper speculates that the ancient ancestors of octopuses arrived at the time when a comet(s) carrying a large number of cellular organisms and genomic information fell to Earth about 540 million years ago, subsequently triggering the "Cambrian explosion of life" on Earth at that time.
It should be noted that due to the lack of conclusive evidence to support it, this view can only be regarded as a reasonable speculation at present, rather than a definitive conclusion, so everyone can just take it and don't take it too seriously.