Large Volcano

It animates on its own and throws off enough light to matter in a dark room, which is why it turns up in lava-themed builds and arena backdrops more than in houses.

The wire input is the part worth planning for. Run it to a switch or a timer and the eruption becomes something you control, so a display room can sit quiet until a pressure plate at the door sets it off. That also lets you kill the animation in a screenshot build where the motion is distracting.