File:Mob Spawner spawning blocks diamond Bedrock Edition - Chicken.svg

Summary
Created using 2 command blocks on a fast timer:


 * /execute at @e [type=chicken] run setblock ~ ~ ~ stained_glass
 * /kill @e [type=chicken]

Chickens are <1 block high and therefore unaffected by the block above - this is thus the base spawner pattern.

Licensing

 * Minecraft screenshot should be covered under fair use for minimal illustrative/educational purposes.