This hollow form is made from a piece of laburnum in side grain. The creamy yellow bit at the top is actually the sapwood of the laburnum, that’s the bit that is right underneath the bark.
This piece was turned and hollowed out, and then carved by hand with hundreds and hundreds of little grooves to achieve the final effect. Just about everybody who gets a chance will pick it up and stroke it gently. The tactile feedback is clearly very important to us as a species.