I talked with the open version of ChatGPT 5 about it:

If you ask for the emoji, it wants to give it to you, but fails to do so.

If you ask why it failed, it explains that there is no official seahorse emoji in unicode.

If you ask why it didn't say that right away, it says that it expected a seahorse emoji to exist.

If you ask why it expected that, it says that its training data leans towards the existence of a seahorse emoji.

If you ask why the training data leans towards its existence, while there is no official one, it says that it must be because many people talked about that emoji in the past.

If you ask why many people talked about it, despite the emoji never existed, it says that humans must have expected it to exist, and that it could be a "mandela effect".

If you ask why unicode has decided to have a shrimp emoji, but not a seahorse, it claims that there never has been a request to introduce a seahorse emoji into the unicode standard.

If you ask why there never has been a request despite the fact that the seahorse is so popular that it's even reflected within the training data, it claims that unicode isn't perfect.

So weird...