Goblins

Goblins would be a mob to spawn in mangrove swamps. They would only spawn in daytime. If a player is within 15 or so blocks of a goblin then the goblin would approach the player(1 at a time so if one goblin is already approaching a player, the rest of the goblins won't approach) and offer a trade by holding out a random item that you can find in caves or something like that. If the goblin holds out an amethyst shard(or maybe one of the blocks that generates clusters as the only way to get one) then the player would need to offer something else that is about as rare if not rarer than what the goblin holds out. (Example: 1 amethyst shard for a block of obsidian or something like that, hard to obtain but easy to find.) If you damage the golblin then they will slowly walk away and the rest of the goblins would sprint away immediately. DESIGN: they would be about 1.5 blocks tall, with their pointy ears making them a total of 1.7 or so blocks tall. Their skintone would be green. They would wear a pair of leather shorts, they would have rings on the bottom of their ears.