These used to be imported by the ton out Baja, up until like 4 or 5 years ago. The larger ones range from 1" to 1 1/4" and glow green even under sunlight in Baja 
The smaller ones in this pic are around 3/4" across, as is the one closed.
This pic is a bit washed out, but it's a decent rendition of the color

The smaller ones in this pic are around 3/4" across, as is the one closed.
This pic is a bit washed out, but it's a decent rendition of the color

