Any thoughts on how to randomly show an image?

I know that this isn't a GP thing, but I have a block that shows an image - all very simple - but what I'd like is for that hook to display a random image (same dimensions) from a pool of selected images

Is there a tool, plugin or method that you'd take to achieve this?

I'm thinking that I should use a plugin then replace the block with shortcode

Any ideas? Anyone done this? Thanks