I can't see your photo (work server blocks most photo sites), but is it a buddha's hand
? Those are the only fruits I can think of that look like Cthulhu.
If so, it's often used as an air freshener! The peel can be candied, zested into salad or pasta or baked goods, or used to make a citron liqueur. Here's a Chowhound
thread's recipe for "Buddhacello." A Google search for Buddhacello will yield a ton of others.
1/4 c grated citron zest
1 750mL bottle of 100 proof vodka
2 c sugar
2-1/2 c water
Put zest and vodka in a glass container, cover tightly, and let steep for about two weeks.
When time is up, make a syrup using the sugar and water.
While it's cooling, strain solids out of vodka using a fine mesh strainer. Then strain again through cloth. (Note: cheesecloth is too coarse; I used rags torn from an old white cotton bed sheet. Be sure to wet the cloth before you start. This step can take a while, but it's worth it to get all the sediment out.)
Add about half the sugar syrup to the infused vodka, taste, and keep adding until it tastes sweet enough to you (traditional limoncello is quite sweet, but yours doesn't have to be).
Pour into pretty bottle(s) (e.g. the final container) and age for another two weeks.