The Blood Yolk (also known as Krakker in the SNES/PS version) is an enemy in Chrono Trigger. First appearing on Death Peak in the Future, these creatures resemble eggs, oozing red liquid from their cracked shells. Additionally, they share similar sprites with Egg Ooze, although the coloration is different; Egg Ooze have shells of an off-white color, with purple goop oozing from the cracks.
Egg yolk is the yellow spheroidal mass of stored food that forms the inner portion of the egg of a bird or reptile and is surrounded by the white albumen. The allusion fits because this enemy resembles an egg. The red fluid excreting from the cracks of the shell may be intended to resemble blood, as the yolk still-born eggs contain blood. Krakkar, the SNES and PlayStation versions of the name, may simply indicate that this egg is cracked.