▁m oll us cs ; ▁and ▁the ▁sed iment ▁that ▁sometimes ▁appeared ▁in ▁the ▁foss ils ▁between ▁the ▁foot ▁and ▁supposed ▁c ten idia ▁suggested ▁the ▁presence ▁of ▁a ▁mant le ▁cav ity . ▁They ▁also ▁concluded ▁that ▁Od ont og ri ph us ▁was ▁closely ▁related ▁to ▁the ▁Ed ia car an ▁animal ▁Kim ber ella , ▁whose ▁foss ils ▁also ▁show ▁signs ▁of ▁a ▁fairly ▁rig id ▁upper ▁" shell " ▁made ▁of ▁a ▁material ▁that ▁did ▁not ▁foss il ize , ▁and ▁which ▁has ▁been ▁interpreted ▁as ▁a ▁very ▁m oll usc - like ▁organ ism . ▁ ▁They ▁went ▁on ▁to ▁class ify ▁the ▁h alk ieri ids ▁as ▁nearly ▁modern ▁m oll us cs , ▁since ▁in ▁their ▁opinion ▁h alk ieri ids ' ▁" chain ▁mail " ▁co ats ▁of ▁min eral ized ▁s cler ites ▁were ▁an ▁advance ▁on ▁the ▁un min eral ized ▁s cler ites ▁of ▁W iw ax ia ▁and ▁also ▁res emble d ▁the ▁arm or ▁of ▁some ▁living ▁shell - less ▁ap lac op hor an ▁m oll us cs , ▁the ▁Ne omen iom or pha . ▁As ▁a ▁result , ▁they ▁concluded ▁that ▁the ▁whole ▁Kim ber ella - O d ont og ri ph us - W iw ax ia - m oll usc ▁line age ▁must ▁have ▁diver ged ▁from ▁that ▁of ▁the ▁ann el id ▁w orm s ▁some ▁time ▁before ▁the ▁appearance ▁of ▁Kim ber ella ▁in ▁the ▁Ed ia car an ▁period . ▁