Clamer (クラマー), renamed Shell Star (シェルスター) in Japan, is a clam-type badnik with a cannon and a pair of staring eyes, created by Doctor Robotnik. It appears at Carnival Night Zone in Sonic the Hedgehog 3.
Once the player approaches Clamer, a cannon appears inside its shell and it begins to fire spike balls. Clamer can also be used as a Spring by bouncing off the back of its shell. The best way to defeat this Badnik is by rolling into it, but it's possible to defeat it with a very accurate Spin Jump.
Clamer appears in Sonic the Comic as part of Doctor Robotnik's badnik army. It was about to be melted down by Robotnik so that its metal could be used for a new improved badnik, after Sonic had foiled one of Robotnik's schemes.