How to make a Block chek if it´s floating?

  1. Sorry for my bad english =)
  2. I´ve made a Block buidling script and everything works fine. But the next thing i want to (and don´t know how to realise) ist how to let them check if they are floatong.

Block =

Simple tower:

<— If i destroy this block, all others above are floating.

I want to to let them know if there are floating or not and if they are they shall replace themself to another object(Block, This one will have a rigidbody). Do you undestand what i mean? I dont want a ready script. Just a main idea how to do that or maybe a tutorial in that direction.

You could raycast down from a block and see if it hits another block within a particular minimum distance depending on how big they are, and if it doesn’t then it’s floating.