There are sea creatures known as xenocongrid eel, xiphias and X-ray fish.
X-ray tetra is a fish species. It begins with the letter x.
jellyfish
Turtle.
dolphin
octopus
quail
anemone
Piranha are a sea creature. Additional sea creatures include prickly shark, Pacific viperfish and pilot fish.
· Unicorn Fish
anemone
· Zebra Shark · Zebrafish
No sea begins with the letter X.