They look like miniature version of "Mexican Coconuts" with more colorful agates in them. Most are hollow geodes containing pinkish psuedomorphs after calcite and barite(?). Some nodules contain agates in a range of colors and fine bandings that they can be confused as Laguna agates. Based on the studies of the Mexican Coconuts, I have came to believe that they may be actually the weathered agate cores of fully expanded thundereggs and the rhyolite shells still attached to the Trancas Geodes and Mexican Coconuts provided some good evidence on that idea. They tend to be small and come in quite a wide range of colors comparable to the other Mexican agates. It's noted that Snowball and Surprise agates refer to the nodules coming from the same location, however, it's possible that there are several different deposits in close proximity to each other which would explain the pinkish geodes mixed in with those showing bluish agate on the surface.

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Rough Appearance: Looks like "Mini-Mexican Coconuts" with multiple ridges and "squashed look"
Blue-skinned agates tend to contain colorful banded agates
Pink skinned tend to be geodes with barite & quartz psuedomorphs