both because some sea creatures eat others. unlike cuttlefish they try to eat eachother.i hope this answers your question.
oyster
The Mediterranean Sea is home to a wide variety of sea creatures. The monk seal, Spanish imperial eagle, loggerhead turtle, Mallorcan midwife toad, shortfin mako, and the Atlantic bluefin tuna all make their home there.
Barnacles and such creatures as those.
Seals
Mother-of-Pearl is found in Oyster shells
Do you mean alive or dead (fossils)?
you can find a pearl inside of a clam
Sea creatures (i think you mean animals) are found in all parts of the sea. However, the pacific ocean holds 1/3 of all ocean wildlife. well mostly the bottom in the deep sea
because most fossils are sea creatures, that are by the sea :)
The home of any animal is their habitat.
Sea creatures from millions of years ago.