You are looking at a material called decaymeat

This material causes an object to be infested with vermin and gradually decay until it erases itself and is gone forever.

Works with tickloc, so decay is arrested when no one is around to see it.

Blocks: tickloc,ticked,decay,zero,slightly,partly,mostly,fully,byebye,kicked,dropcoins

Note: if the corpse has some worth, and someone kicks it, then it will create a pennies object that is worth a random part of the original object's worth, while deducting its own worth. Even if there is no worth, it makes a disgusting squishy sound.

Coders: Note the use of matvals to keep a counter. If we do it this way instead of using the counter field then you can have multiple materials that don't walk over each other's counters.

Customizing
On the final decay phase, just before erasing the object, the block deathbydecay is called. Create this block in an object with this material on it to do something appropriate.

An example: read the material called leadquest


Code