Hello Mr. Mei :p
... ocean life in Oceana was discoverDISCOVEREDof an Atlantic lantern Shark which hasHADlongLENGTH 20 centimetres CENTIMETERS and glowing bright blue GLOWED BLUE BRIGHT along its spine ...
1. WAS + DISCOVER ---> DOUBLE VERB , DISCOVERED ---> VERB 2, "menemukan"
2. HAS ---> HAD , since this occurence in the past time
3. LONG ---> LENGTH, long (adjective), ====> length (noun)
4. TYPO --> CENTIME"TERS"
5. GLOWED (VERB PAST) + BLUE (ADJ, color) + BRIGHT (NOUN, lampu)
and they are WERE very surprising because they are discoverTHEIR DISCOVERY OF an ocean environment isWAS almost completely unexplored and inventINVENTED several species which WERE very exciting.
6. ARE ---> WERE (PAST TENSE)
7. THEIR DISCOVERY OF ( I looked at your sentence structure, and it must be like that to make it correct)
8. IS ---> WAS (PAST TENSE)
9. INVENT ---> INVENTED (PAST TENSE)
10. WHICH + WERE (VERB) ---> don't forget to place your verb there.
Dioba, please make sure you know the TIME SIGNAL of the article, Present or Past.
Then, please study again about subject verb agreement.
Break A Leg !