According to wikipedia, (and the little package they came in), these are finger limes. Appropriately named for their size and shape, this citrus australasica grows mainly in Queensland, Australia. They have a distinctly strong zest, and inside, the pulp is round and bright green. The juice inside each piece of pulp is sour, but not unpalatable like that of a true lime. Almost comparable to fish roe or caviar, the little beads of citrus burst in your mouth!
I have yet to use these lovely little finger limes in my cooking, but the lime that I had by itself was a refreshing little treat! I imagine the zest would be great to add in a ceviche, fruit salad, baked fish or grilled chicken, pork, added to cheesecakes or sorbets, or wherever a little burst of citrus and texture is needed!
If you ever see these, you have to try them! They are amazing and just show the unique and beautiful nature is.