Pyukumuku is a stubby, black marine Pokémon with a round body, beady pink eyes, and a distinctive star-shaped white mouth. It's best known for its weird ability to shoot its organs out through its mouth—they can form different shapes, like a fist. Two rows of pink spikes run down each side of its back, with the middle spike in each row noticeably longer than the rest. Its tail is just a fluffy white puff.
This Pokémon is stubborn to a fault. It picks a spot, claims it, and refuses to leave—even if you move it elsewhere, it'll try to return to that exact location. More problematically, it'll starve to death rather than abandon its favorite spot once the food runs out. Its body stays moist thanks to a slick, viscous coating that keeps it alive on land for about a week without drying out. This same fluid actually works as a decent moisturizer for humans, which is one of the few practical perks.
Pyukumuku gets stepped on constantly because tourists find it ugly and unpleasant, and it doesn't help that the Pokémon just sits there. When threatened this way, it punches back using those fist-shaped organs. It's particularly touchy about its mouth and spikes being touched. The situation got bad enough on beaches that part-time jobs literally exist to pick these things up and throw them back into the ocean. In Alola, people have realized they can just toss Pyukumuku back when it starts looking thin, letting it find food in the water. There's also an interesting symbiotic thing going on with Pelipper, which will scoop Pyukumuku up and carry it around.
Content compiled by AnimeList.moe from publicly available sources.