I've rejected Jellyfish Idea and came up with this idea, they may be "similar" ideas but they won't be clichéd:
• they swim (obviously)
• when you kill them, they drop their tentacles
• you can craft the tentacles by looking like you're making a sword but replace the material of the sword with the tentacles to make a whip, extra range and it also can display a weapon that people sure don't wanna mess with when someone has it
• they can be picked up in a bucket (like any other fish)
• if Mojang can code the head not hurting you but the tentacles hurting you!
• they usually spawn in red, green, and blue variants
• OOOOH, this is the best part! You can dye them to whatever color dye you want! If you think that it's over-the-top, why don't you tell me that the sheep's color dye being dyed? That wasn't over the top, wasn't it?
The Meaning of Life, the Universe, and Everything.
I know this is over a week old, but I'm replying anyway.
This is pretty underdeveloped. So yeah, this whip... you told us nothing about it except has extra range and "no one will mess with you"... Okaaaaay..? That's not how you present a weapon. Range (in blocks)? Damage? Durability? Etc? You didn't give much numbers/stats on the jellyfish either. I don't see anything 'bad' in the idea and I can very mildly support it, but for the record - and not that it's the end of the world or anything - but it's best to leave out generic lines like "they'd be cool to add".
I mean, yeah... It's pretty obvious you're gonna think your own idea is cool, hence why you posted it. This next part I'm adding just for the sake of adding, but always remember that a person's own opinion on an idea is always the weakest.