A photorealistic street art mural of a massive octopus with deep midnight purple skin and iridescent suckers spreading across the crumbling walls of an abandoned aquarium, its tentacles rendered in hyperrealistic spray paint with wet shine and muscular texture, faded blue light filtering through broken tank glass casting soft underwater glow across cracked tiles, mood mysterious and intelligent yet forgotten, composition radial with tentacles reaching outward filling the empty space, scattered broken filter systems and toppled feeding stations creating marine decay, color palette deep purples and ocean blues contrasted with warm amber light from broken entrance doors and soft coral pink accents