Question Summary
Since it is impermissible to eat clams, does that mean they are impure, just like impermissible animal meat?
Answer:
In the Name of Allah, the Most Merciful and Compassionate
Even though clams are impermissible to eat in the Hanafi school, they are not impure. [‘Ayni, al-Binaya Sharh al-Hidaya]
This is because clams do not have flowing blood in them, similar to fish. [‘Ayni, al-Binaya Sharh al-Hidaya citing al-Sarakhsi]
For this reason, the slaughtering of an animal according to the conditions of Islamic slaughter removes the flowing blood from the meat, thus leaving it pure; whereas, fish are not slaughtered because they do not contain flowing blood that needs removing.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani