I live in Minnesota and have grown squash for years. This year, I planted some Loofah squash, which I'm not sure can even mature in our climate!, aways away from the other squash.
Now, I have two bushes, like zucchini bushes - one central axis - of squash that look like long, immature pumpkins. They taste sweeter than zucchini. I vaguely recall buying something other than "black beauty" zucc seed, but I have no idea what this is. Inside, it almost looks like it could be loofah - which I have never grown before and am not familiar with, other than I thought Loofah grew on a vine... I think both are edible.
Could I have a cross? Is it loofah? Is it something else? A different variety of zucchini?
Both are fibrous and seedy inside, the Mystery squash moreso. The normal Zucchini has a little more 'flesh'.
*Squashes: Zucchini, top. Mystery squash, bottom.
*Cross sections: Mystery squash, left. Zucchini, right.
*Single shot: the mystery squash, interior
The luffa acutangula I grew had leaves like dinner platters and they had fruits that were edible about the 8" length but better at 12", it looks like you had a dry stunted zuke, not a luffa, cukes get that pithy inside when not watered enough and not gathered til overripe.
I have some squash that look exactly like yours. I planted one zuchinni, several spaghetti squash. It turns out that among my spaghetti squash was a pumpkin seedling. And they all cross pollinated! Now I have quite a variety, including some that look like yours. I am going to take a picture of all of them and post in the next few days.