I made a block that looked like a slime. By modifying terrain.png.
I created the block "slime" on my server and this was the result.
Then, I used /model so I could turn into the block "slime"
Then I discovered a plugin that spawned mobs
I modified the plugin and it spawned slimes as a hostile mob
And it worked!!!
This works with any block/custom block
When I was taking screenshots, the slime killed me