▁Bol to v sky ▁et ▁al ▁is ▁of ▁an ▁egg - sh aped ▁central ▁caps ule ▁( the ▁part ▁of ▁the ▁cell ▁containing ▁one ▁or ▁more ▁nuc lei , ▁Gol gi ▁bodies , ▁mit och ond ria , ▁l ys os om es , ▁and ▁other ▁bodies ▁important ▁for ▁cell ular ▁function ) ▁located ▁within ▁a ▁por ous ▁con ical ▁ske leton ▁made ▁of ▁sil ica . ▁The ▁central ▁caps ule ▁is ▁typically ▁located ▁toward ▁the ▁ap ical ▁end ▁of ▁the ▁ske leton . ▁The ▁bas al ▁end ▁is ▁usually ▁in ▁the ▁shape ▁of ▁a ▁h ollow ▁circle , ▁giving ▁the ▁ske leton ▁a ▁con ical ▁look . ▁S urr ounding ▁the ▁central ▁caps ule , ▁but ▁still ▁inside ▁of ▁the ▁ske leton , ▁is ▁the ▁ext rac aps ul um . ▁This ▁material ▁is ▁primarily ▁al ve oli , ▁gas - filled ▁b ubble - like ▁structures ▁that ▁reg ulate ▁the ▁bu oy ancy ▁of ▁the ▁organ ism . ▁The ▁al ve oli ▁are ▁connected ▁by ▁a ▁web ▁of ▁rh iz op odia ▁throughout ▁the ▁ext rac aps ul um . ▁F us ules ▁connect ▁the ▁int rac aps ul um ▁( central ▁caps ule ) ▁to ▁the ▁ext rac aps ul um . ▁Ax op odia ▁and ▁additional ▁fus ules ▁extend ▁out ▁of ▁the ▁bas al ▁opening ▁and ▁through ▁the ▁por es ▁in ▁the ▁ske leton . ▁These ▁will ▁act ▁as ▁feed ing ▁appar atus es ▁for ▁the ▁n ass ell arian . ▁▁ ▁ske let ons ▁ ▁There ▁exist ▁three