Breakable Blocks were introduced in the first Xysspon game, and have appeared in every single installment of the Harpy Series.
They are able to be broken with any projectile, but also can be destroyed when stood on.
Harpy Gaiden introduced the blocks actually falling when the player stood on them rather than just breaking. Harpy Gaiden DX implemented the ability for enemies and explosions to break these blocks.
Breakable blocks are light colored cubes with a rounded cube indent in the middle of them.
Their color is either light grey or light beige.