piano chord
E♭dim7
E♭1G♭♭3B♭♭♭5D♭♭♭♭7
Three minor thirds stacked. The seventh is doubly diminished, which is why it is written with a double flat.
Written the other way round it is D♯dim7 — the same twelve keys on a piano, a different piece of notation.
What is true of it
E♭dim7 is E♭, G♭, B♭♭ and D♭♭ — 1, b3, b5 and bb7 counted from E♭.
B♭♭ and D♭♭ are double flats, and they have to be: every letter from E♭ upwards is used once, so the b5 cannot be written any other way.