Not knowing what a giga clam is, I Googled it and came up with this :
"The Giga Clam is an enemy that can be found in the Aquatic Depths Biome. It remains stationary and periodically shoots 3 pearls upward in a cone shape. The pearls can travel for 5 seconds before popping, and are destroyed upon colliding with blocks. The pearls inflict rather high damage, but are easily avoidable. The Giga Clam itself can also inflict contact damage."
Sounds cool, but will I need to bring blocks the next time I visit your basement? *lol*