Best way to drill a hole in a cowry and conical shell?

Generally, I figure you submerge a shell in water and use a dremel with a diamond bit or tile cutter bit or some other bit for hard materials to make the hole.

This sounds like it would work fine with shells that have a sizable flat surface exposed for drilling the hole, but cowries and conical shaped shells don’t have this.

I’ve read several different approaches that involve filing down or cutting out the ‘guts’ of the shell. I’d rather keep the thing intact and really just want to make a hole.

2 questions:

1. What is the best way to go about it?

2. Does submerging the shell in water while drilling sufficiently prevent stress cracks from forming? Or is it typically necessary to start with a very small hole and slowly enlarge it?