Nautilus have unshaded/untextured spots

The Bug:

The Nautilus mob has some areas that are either not shaded, or not completely textured, namely on the baby nautilus and zombie coral nautilus.

Example 1:

The adult nautilus as a completely textured underside, however the baby nautilus has a completely flat, unshaded underside.

On the adult this shading is simply done by flipping the top texture onto the bottom, the same could be done for the baby

Example 2:

The zombie coral nautilus has two areas where the coral lacks continuity and seems to just cut off at the edge of the model, similar to the old cow patterns.

Example 3:

The zombie coral nautilus also has a spot of coral that appears to be entirely unshaded