Shellgeek

 ShellGeek is a virus from the Mega Man Battle Network series. It looks like an oyster. It often hides its shell unless it open up to shoot out needles. It will shoot more than one needle at a time.

ShellGeek
 ShellGeeks are red and shoot out two needles at a time.

ShellNerd
 ShellNerds are yellow and shoot out three needles at a time.

ShellMan
 ShellMans are purple and shoot out four needles at a time.