. ▁The ▁play ground ▁has ▁been ▁converted ▁into ▁a ▁park ▁of ▁pet r ified ▁tree ▁tr unks . ▁A ▁relatively ▁sp a cious ▁room ▁inside ▁the ▁school ▁has ▁on ▁display ▁foss ils ▁of ▁marine ▁in verte br ates , ▁fish , ▁and ▁m amm als , ▁as ▁well ▁as ▁some ▁ancient ▁artifact s . ▁ ▁The ▁foss ils ▁The ▁tree ▁tr unks , ▁ 5 – 1 0   m ▁long ▁and ▁ 4 0 – 8 0   cm ▁in ▁diameter , ▁come ▁from ▁the ▁N ost imo ▁Pet r ified ▁Forest , ▁which ▁consists ▁chief ly ▁of ▁tropical ▁and ▁subt rop ical ▁plants . ▁The ▁forest ▁grew ▁in ▁delta ic ▁all uv ial ▁depos its ▁of ▁the ▁pre histor ic ▁T eth ys ▁Ocean , ▁which ▁was hed ▁the ▁wider ▁area ▁of ▁K ast oria . ▁The ▁foss il ised ▁trees ▁are ▁of ▁Early ▁Mi oc ene ▁age ▁( 1 5 ▁to ▁ 2 0 ▁million ▁years ▁old ), ▁and ▁are ▁in ▁excellent ▁condition ; ▁most ▁of ▁them ▁are ▁pal m ▁trees . ▁ ▁The ▁marine ▁foss ils ▁consist ▁of ▁star fish , ▁sea ▁ur ch ins , ▁con ches , ▁wh el ks , ▁scal lo ps , ▁muss els , ▁other ▁se ash ells , ▁and ▁other ▁marine ▁in verte br ate ▁foss ils ▁that ▁are ▁in ▁near ▁perfect ▁condition . ▁The ▁verte br ate ▁foss ils ▁include ▁a ▁j aw ▁and ▁teeth ▁of ▁a ▁sh ark ▁that ▁was ▁ 2 0 – 2 5   m ▁long ,