No, they don't cross. It looks like you let your cucumbers stay on the vine too long. If those are cucumbers they are pickling types that should have been harvested a week ago. You do not wish either zukes or cukes to develop seeds. They are used as immature fruits.

The skin and stem look more like zucchini to me than cucumber. Either way it is definitely over mature.

Did you give it a taste? It's shaped like spaghetti squash but doesn't have the same outer appearance. Definitely a squash and not a cuke because cukes don't have stems like that.

Do you have any seeds left for reference? I agree that those are not of the cucumber species. The stem width, skin color and seed size say squash.

Cuke seeds are pointed, smooth and almost shiny, and much narrower than zucchini seeds. You could have gotten a mislabeled seed lot.

Taste it. If tastes like cucu let it ripen, it can then be eaten like a melon, slightly sour sweet taste. If tastes like squash, then it is some variety of squash and cook it like one. From the appearance, it is most likely a squash or pumpkin of some kind. Let it grow more and see what it turns out to be.

Here is link that might be helpful:

http://www.ehow.com/how_8525906_identify-cucumbers-squashes-melons.html

Did you grow these from seed, or purchase starts on them? Let's see the skin on these veggies please? The stem doesn't even look like a cuke stem. If they were pickling cukes, there'd be little nubby spines on them. I don't think they are cukes and they look too 'dry' to be cukes, even over ripe ones. If you bought them as plants, it appears they've been mis-labeled.

Lol, i'm so confused! Thank you to everyone for your responses. Is it an overripe cucumber? Or an underripe zucchini? ;-). They were started from seed. Not sure what happened the day we planted,. Because when seedlings started to come up, they were spread all over the garden! All the seedlings looked similar. I could not tell the difference between the cucumbers and squash as they were coming up. It wasn't windy that day, perhaps water pressure dispersed them. I have plucked these at various stages, and they all seem to have the same meat inside them. Just a smaller variety when younger! :-). I keep all my seed packets after planting, however, my boyfriend must've thrown the cucumber packet away. He was the one that planted the cucumbers. I'm sorry, did I mention he is an ex boyfriend! I smell sabotage!!! Picture of younger cucchinni (I may patent this if a new variety, lol. What do you think of the name? ;-) ) with one of my distinguishable zucchini

Zucchini or cucumber or cuke the specimen is overage. You don't want a ripe one of either. The additional photos confirm that it is some sort of squash. Does it vine? zucchini will be a bush plant. Trailing vines would indicate a winter squash. I am not aware of a zuke with that physical appearence.

Looks like a cross between a watermelon and a zucchini... not possible though.

Lemon cucumber?

I'm not sure what it is but it's definitely not a lemon cucumber.

Rodney

If you gardened last year and grew squash and perhaps pumpkins, it seems reasonable to imagine that some of these are a cross from last year's plants. It appears that you actually have at least one zucchini because you have a far overgrown one on the left. The others are probably the last year cross. They are often useless.

Stem of your mystery fruit in last pic just looks like an overripe cucumber to me. Do you have a pic of a tiny one on the vine??

Tha zucchini on the left is also overly ripe and should have been picked younger for most purposes.

It looks like an immature spaghetti squash, which starts out green-striped and finishes light yellow.

That appears to be an unripe spaghetti squash.