Some informations that I believe may help you.
ELEPHANT IVORY:cross sections of elephant tusks display a distinctive pattern of intersecting curved lines,resembling the patterns producedby "engine turning".Longintual sections show a pattern of wavy , sub-parallel stripes
WALRUS:It has an oval cross section with an outer coating of cementum and a large pulp cavity in the centre which runs throughout its length.This central cavity consists of coarse bubbly or nodular material.
BONE:Resembles ivory closely in appearence but is distinguished by its structure.Bone contains many small tubes which are seen as dots in cross section or as lines in longitudinal sections.They are most clearly seen where filled with dirt.
VEGETABLE IVORY
erives from the nuts of certain palm trees(Coroso nut) from South America and (Hyphaene Thebaica) South Africa.Cross sections show a pattern of faint concentric lines,longitual sections show a pattern of parallel lines.Since the pulm nuts are small in size aprox 2cm to 3cm objects are generaly small.
I hope not to confuse you too much.Try the next pics .
1.Cross section elephant ivory
2.Longintual section elephant ivory
3.Vegetable ivory
4.Walrus cross section
5.Walrus cross section