If it helps, here are some pics of the tree itself...

Seedless key lime???

Sounds like maybe a Bearss lime? I know they are supposed to be yellow, sweet, and seedless??? Or maybe a Palestine? Hopefully someone can "NAME THAT LIME" hahaha

You're right. Lemon/lime hybrids are characterized by being larfer than limes, smaller than lemons, being both green and yellow (green unripe, faded when ripe) and conspicuously lacking in juice. You do, indeed, have a lemon lime hybrid. Here's the thing. They (allegedly) do not occur in nature, only through forced hybridization. Try to find out how the tree got there, in the first place. That should help. (Note: various strains of lemons and limes exist. What combo is it? You need to find a botanist to assist you with its genaeology)

P.s. Bearss limes are sweet, with a lime bight, and have avg amount of juice, for a lime. A hybrid would be dry, and not sweet. If it's dry, and lacking in the flavor dept, it's a hybrid. Sweet, limey, and moist, it's a Bearss... Hope that helps...

"Bearss limes are sweet"

No, not any I've ever tasted! Very acidic, typical lime flavour.

See https://citrusvariety.ucr.edu/citrus/bearss.html

I once had an in ground Bearss lime tree. I can tell you that Bearss limes definitely are not sweet.

Lemonimes

Lemonimes

I'm guessing you are making up a word, but is also a Lemon Brownie. I wonder if you actually have a larger Mexican lime that has a variety sizes for the fruit. When a Mexican gets ripe it is yellow, mild tasting and less sweet... it's called a Key Lime when ripe and is frequently made into a delicious pie; and other yummy desserts.

Persian limes (also known as Bearss, the variety commonly sold in stores while green) will ripen to yellow if left to hang on the tree. This looks identical to my Persian limes once fully ripe. It is a hybrid of a key/mexican lime and a lemon.