Bullia digitalis proboscis into the prey to suck up soft tissues. Often gathers in large numbers to feed on dead and stranded jellyfish and bluebottles. Various plough shells on the southern African coast look similar, including "Bullia rhodostoma" on the south coast and "Bullia natalensis" (pleated plough shell) on the coast of KwaZulu-Natal. "B. digitalis" however does not have pleated whorls like the pleated plough shell. All the common plough shells on the coast can only de differentiated for each other by their colour. Bullia digitalis Bullia digitalis, the finger plough shell or plough snail, is a species of sea snail, a
Derive (computer algebra system) Derive (computer algebra system) Derive was a computer algebra system, developed as a successor to muMATH by the Soft Warehouse in Honolulu, Hawaii, now owned by Texas Instruments. Derive was implemented in , also by Soft Warehouse. The first release was in 1988 for DOS. It was discontinued on June 29, 2007 in favor of the TI-Nspire CAS. The last and final version is Derive 6.1 for Windows. Since Derive required comparably little memory, it was suitable for use on older and smaller machines. It was available for the DOS and Windows platforms and was used also in TI pocket