Mantis Bio Blacks are premium ceramic filter blocks engineered for superior biological filtration across all aquarium setups. Each inert ceramic block features an open-flow design that maximizes surface area—1080m² per block—enabling efficient conversion of ammonia and nitrate. Ideal for sumps, trickle filters, wet/dry systems, hang-on-the-back filters, or direct tank placement, these blocks work seamlessly in freshwater, marine, and pond environments. Two blocks per box; dimensions 10×10×2.5 cm. A technically advanced substrate choice for serious hobbyists seeking reliable, long-term biological stability.