The metals in the ash of seaweed have been shown to produce a significant catalytic effect on pyrolysis, and ash content (especially potassium salts) strongly influences the product yields and bio-oil properties (Milledge et al. 2014). The addition of bone meal will add inorganic matter and alter the mineral balance, thus having an influence on pyrolysis.

Milledge JJ, Smith B, Dyer P, Harvey P (2014) Macroalgae-Derived Biofuel: A Review of Methods of Energy Extraction from Seaweed Biomass Energies 7:7194-7222

As far as I know, potassium increases the char content and calcium increase the reaction rate and decrease the maximum degradation temperature. You need to check the ash forming elements in bone meal if it has high concentration of calcium and potassium. So the higher the potassium the  higher the char content.

Additionally, bone meal might contain high concentration of calcium so you can check if lower degradation temp. in pyrolysis improves the quality of bio-oil. 

I strongly agree with the ideas of colleagues Milledge and Shoulaifar.

(refs. to works like those of Garcia Maraver et al.)

Thanks to Tooran, John and Marzouk for your answers, I have checked and discover that bone meal contain about 18 wt% of calcium and 62 wt% of bone meal is ash. any idea on how this could lead to low degradation temperature in pyrolysis as proposed by Tooran?