crimson = corruption
i figured this out after i released the crimson's enemy ai is nearly identical to corruption, and the fact that you break "hearts" instead of orbs is similar as well.
Your world will only spawn one or the other, just like you may only get mythril instead of the new, pink ore. They work the same, but serve different aesthetic purposes.
ALSO WHAT THE forget DID I JUST FIND

my world had a "solar eclipse" and then i was smashing a stuffload of monsters when a grim reaper dropped this.