Vine

Vines are climbable level elements that can be modified in height. You can also put them in blocks that items can be put in, and they will continue growing until they reach a ceiling. If they have no room to grow upwards, they grow downwards. If they are hit from above (ground pounded or if it is a note block), they will grow downwards unless they have no space, then they grow upwards. If they have no space to grow either way, they won't grow.