Sea Whelks are tiny gathropods who's appearance was huge because they were sick. They only appeared in Whelk Attack. They attacked the city by blowing a bubble large enough to capture people and buildings from Bikini Bottom. They have eaten the Krusty Krab and other buildings and they people they have eaten were SpongeBob, Patrick Star, Sandy, Squidward, Mr.Krabs and other Bikini Bottom citizens. They are similar to snails. Their shells look similar to hermit crab shells. When they were cured, they have baby mammoth sounds.
 Mother Sea Whelk
The Mother Sea Whelk is the leader of all of the sea whelks who attacked the city. When she and her group was cured by Sandy they turned back to the tiny size and she is still bigger than the rest of the group.
 Whelks' Appearance
All of the sea whelks have yellow-orange shells, have purple skin and they have no eyes.