A big magenta nipper, one of the four rare catches the Fisherman wants, and your ticket to a Holy Talisman piece.
The Lobster is one of four rare fish standing between you and a Holy Talisman piece. It is a magenta, two-pincered catch that the Fisherman prizes, and it barely shows up unless you fish for it deliberately.
It is a quest item first and food second. According to the wiki, the Lobster is used in the Fisherman's Quest to earn a Holy Talisman piece, one of the pieces you need for the endgame.
Catching it is the tricky part. The wiki notes the Lobster comes from the Small Fish Silhouette and is far easier to hook with the Ritual of the Ocean's Bounty active.
This guide covers what the Lobster is, how to catch it, its role in the Fisherman's Quest, and every other use for it.
A rare fish resource, described as a big nipper.
From the Small Fish Silhouette, ideally under Ocean's Bounty.
The Fisherman's Quest, for a Holy Talisman piece.
The Mighty Meat Feast, a three-star meal.The Lobster is a food resource, but one of the rarer ones. Per the wiki it is a round magenta lobster with two pincers and two mandibles, flavor-tagged as "a big nipper" and meant for the wealthy or well behaved.
It sits with the other prize fish. According to the wiki, the Lobster is one of four rare catches, alongside the crab, octopus, and squid, that the Fisherman sends you after.
On its own it is worth some Coin. The wiki lists the Lobster as selling for 20 Coins, and the Fisherman later sells it back to you for 30 once you have finished his fishing questline.
You catch the Lobster by fishing, not by luck alone. Per the wiki, it is pulled from the Small Fish Silhouette, the smaller ripple that appears at fishing spots.
The best fishing is at Pilgrim's Passage. According to the wiki, the Fisherman starts in 
Darkwood but sends the Lamb to Pilgrim's Passage, where the best fishing, and the rare fish, live.
One ritual makes it far easier. The wiki states the 
Ritual of the Ocean's Bounty sharply increases the catch rate of rare fish, so the Lobster and its three cousins turn up much more often with it running.
Run Ocean's Bounty before a fishing session. In practice the rare fish are hard to find without it, so timing the ritual with a dedicated fishing trip is the fastest way to complete the Fisherman's Quest.
The Lobster's whole point is the Fisherman's Quest. Per the wiki, the Fisherman, a flounder in a fake human nose, asks the Lamb to catch four rare fish: a crab, a lobster, an octopus, and a squid.
Each fish pays out a Holy Talisman piece. According to the wiki, you get one Holy Talisman piece per type of fish delivered, making the Lobster a direct step toward the endgame.
Finishing it opens a shop. The wiki notes that once all four rare fish are caught and handed in, the Fisherman becomes a shopkeeper who sells every type of fish, and he even gifts the Neptune's Curse 
Tarot card when the quest begins.
Catch crab, lobster, octopus, squid One Holy Talisman piece per fish type Fisherman becomes a fish shop (plus Neptune's Curse)Outside the quest, the Lobster is premium cooking material. Per the wiki, it goes into the Mighty Meat Feast, a three-star meal that keeps your 
followers well fed and content.
It is also just valuable. According to the wiki, the Lobster can be gathered from Offering Statues as well as fishing, and its 20-Coin sale value makes surplus catches a decent income source.
Once the quest is done, it is buyable. The wiki notes the Fisherman sells the Lobster for 30 Coins after his questline, so you never have to rely on the Small Fish Silhouette again for a three-star recipe.
The Fisherman is a fish pretending not to be. Per the wiki, he wears a fake human nose and mustache and catches himself calling the Lamb a fellow non-fish friend, a running gag behind the Lobster quest.
The rare fish barely exist without the ritual. According to the wiki, outside the Ritual of the Ocean's Bounty the crab, lobster, octopus, and squid are hard to find, which is why so many players stall on the quest.
The Lobster ties fishing to the endgame. The wiki frames the Holy Talisman pieces from the Fisherman as part of the path toward 
Narinder, so a humble crustacean feeds directly into the main story.
The Lobster ties fishing, cooking, and the endgame together. These guides cover the recipes it feeds, the ritual that makes it catchable, and the ocean it swims in.
Game data and screenshots adapted from cult-of-the-lamb.fandom.com, used under CC BY-SA 3.0. Original content remains the property of the wiki contributors and Massive Monster and Devolver Digital.