Sandita (aka little watermelon), Mouse melon, Mexican sour gerkin, or cucamelon. This crunchy slightly sour cucumber bite hails from Central and South America. This is one we prefer to grow in the greenhouse as it is slow to establish. However, once it gets going, you can easily pick up grape sized fruit from off the ground when they are most ripe or off of the prolific vines. The plants have cute little leaves and are more resistant to disease than other cucumber crops. Quite drought tolerant.
Photo and description thanks to: High Desert Seed + Gardens