It seems that the top of the booster fell off when the booster tipped over after a wave hit the droneship. Hopefully not typical.
The bottom portion (RP-1 tank), the landing legs, and the engines stayed on the ship. Octagrabber sustained some damage.
Photos from various Florida Spaceport photographers:
Videos from NSF Space Coast Live:
They should make it out of stainless steel with sub 10-micron tolerances.