Vintage US and Euro tubes, including guitar tubes and rare triodes. It has black plates, top getters, and a metal collar base. This s GE WB is a military spec tube.
The ancestors of present-day insects were probably worm-like arthropods with a simple mouth opening near the front of a bilaterally symmetrical body. Over many eons of time, tissues and appendages near the mouth opening came to be adapted for gathering and manipulating bits of solid food. As insects evolved, they became more complex, expanded in range, and adapted to new food resources. The structure and function of their mouthparts changed right along with their evolving diet and life style.