spring
氿 centers on a natural water source: a spring where water emerges from the ground.
氿 combines 氵 (water) with 九, which likely contributes the sound. The exact historical development is uncertain, but the component structure suggests a phono-semantic origin related to water.
Water 氵 beside the number nine 九: imagine nine small springs bubbling up side by side.
For キ, picture a key floating in a spring: key -> キ, and the water bubbles around it.