In the ayah al-Maa’idah 5:96: “Lawful to you is (the pursuit of) water-game and its use for food – for the benefit of yourselves …” So seafood, anything that lives in water are permissible for us to consume.
I love seafood, especially different shells, squid, crab and fish. When I went to the city in China which is next to the sea, seafood was everything that we are eating when we are there, and they are so cheap! There were shell tofu soup, steamed fish with scallion, crab meat and roes, squid, so delicious!
All praise be to Allah, these are the blessings that he has bestowed upon us, for us to consume such varieties of seafood. ALL kinds of food from the SEA are permissible, whether they are plants or animals, alive or dead. Note that we can concume crabs although they live both on land and in sea, they don't have any blood. Certain types of water animals are not allowed to consume, including water and land mix animals, amphibians. For instance:
None of the above mentioned are typical everyday seafood that we see. So as long as we are not consuming weird seafood that we never heard of or never seen before, we wil be fine.