Esmerelda is a sea snail that appeared in the episode "Sanctuary!" She was mistaken for a male by SpongeBob and nicknamed "Señor Poopus".
- Aliases — Señor Poopus (by SpongeBob), Señorita Esmerelda
- Gender — Female
- Friends — SpongeBob SquarePants, Gary the Snail
- First appearance — Sanctuary!
She is similar in appearance to Gary. However, she has a light green body with a yellow underside, a light purple shell with ten blue spots, and thick eyebrows. She appears to be a stray snail in bad shape, as indicated by her withered eyestalks, visible ribs, and a dent in her shell.
In "Sanctuary!" SpongeBob and Gary come across Esmerelda hiding behind a rock. Shy at first, she is quickly befriended by SpongeBob, who takes her home, names and feeds her.
- She is voiced by Dee Bradley Baker