It was created for underwater robotic vehicles
Murex Robotics, a robotics team based at Phillips Exeter Academy in New Hampshire, claims to have developed the smallest and most affordable network switch ever made. Moreover, it is also very cheap.
This square device, called mrxSwitch v2.0, is about three fingers wide and costs just $7. It has five Ethernet ports with a speed of 100 Mbps and is characterized by dimensions of 44.9 x 42.2 mm. Most network switches of this size are designed for highly specialized embedded systems, but Murex has created its switches specifically for use in underwater rovers and robotic submarines.
mrxSwitch V2 — It is the world's smallest network switch and dwarfs all commercially available options in size and cost. Its potential use cases include, but are not limited to, embedded systems, ROVs and AUVs, consumer electronics, DIY projects, and other space-constrained network devices
A tiny board allows computers such as a Raspberry Pis or NUC to communicate with all the cameras, motors and other instruments needed to control an unmanned underwater vehicle. Featuring compact 4-pin Molex PicoBlade connectors instead of bulky RJ-45 ports, the device fits well into the cramped interior of a waterproof robot case.