Sticker Entity

[evildogbot100]

What are they?

[Choumiko]

If my memory serves right they are used to slow biters down after throwing a slowdown capsule.

[evildogbot100]

Are they only usable for modifying movement speed?

[Mooncat]

They can also deal damage to the attached entity, like the fire sticker in fire.lua
It is also possible to set the speed modifier negative to make the entity moves backward.