tie in old items and features with new ones

you should make a drop where old items that have a niche use or don't have one at all connect to new features like for example you should add a mob like the prismarine golem which can be found in these alter structures made of various prismarine blocks, it should start out as a statue and if you put a heart of the sea in its chest it turns into a fun mini boss where if you try and swim away it pulls you back in and you can only deal damage to the heart of the sea in its chest, when you defeat it the heart of the sea will pop out and it will turn back into a statue and you cannot put in another heart of the sea, once it does you can put a nautilus shell in its chest to tame it and have it automatically attack any underwater hostile mobs including guardians and it could disable the mining fatigue when you get close to an ocean monument.